Changes for page 12 Validation and Transformation Language (VTL)

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  == 12.1 Introduction ==
--The [[Validation and Transformation Language>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] ([[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]]) supports the definition of Transformations, which are algorithms to calculate new data starting from already existing ones{{footnote}}The Validation and Transformation Language is a standard language designed and published under the SDMX initiative. VTL is described in the VTL User and Reference Guides available on the SDMX website https://sdmx.org.{{/footnote}}. The purpose of the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] in the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] context is to enable the:
++The Validation and Transformation Language (VTL) supports the definition of Transformations, which are algorithms to calculate new data starting from already existing ones{{footnote}}The Validation and Transformation Language is a standard language designed and published under the SDMX initiative. VTL is described in the VTL User and Reference Guides available on the SDMX website https://sdmx.org.{{/footnote}}. The purpose of the VTL in the SDMX context is to enable the:
  * definition of validation and transformation algorithms, in order to specify how to calculate new data from existing ones;
--* exchange of the definition of [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] algorithms, also together the definition of the data structures of the involved data (for example, exchange the data structures of a reporting framework together with the validation rules to be applied, exchange the input and output data structures of a calculation task together with the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformations describing the calculation algorithms);
--* compilation and execution of [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] algorithms, either interpreting the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformations or translating them in whatever other computer language is deemed as appropriate.
++* exchange of the definition of VTL algorithms, also together the definition of the data structures of the involved data (for example, exchange the data structures of a reporting framework together with the validation rules to be applied, exchange the input and output data structures of a calculation task together with the VTL Transformations describing the calculation algorithms);
++* compilation and execution of VTL algorithms, either interpreting the VTL Transformations or translating them in whatever other computer language is deemed as appropriate.
--It is important to note that the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] has its own information model (IM), derived from the Generic Statistical Information Model (GSIM) and described in the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] User Guide. The [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] IM is designed to be compatible with more standards, like [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]], DDI (Data Documentation Initiative) and GSIM, and includes the model [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] that can be manipulated (inputs and/or outputs of Transformations, e.g. [[Data Set>>doc:xwiki:Glossary.Data set.WebHome]]", "Data Structure") and the model [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] that allow the definition of the transformation algorithms (e.g. "Transformation", "Transformation Scheme").
++It is important to note that the VTL has its own information model (IM), derived from the Generic Statistical Information Model (GSIM) and described in the VTL User Guide. The VTL IM is designed to be compatible with more standards, like SDMX, DDI (Data Documentation Initiative) and GSIM, and includes the model artefacts that can be manipulated (inputs and/or outputs of Transformations, e.g. "Data Set", "Data Structure") and the model artefacts that allow the definition of the transformation algorithms (e.g. "Transformation", "Transformation Scheme").
--The [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] language can be applied to [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] by (% style="color:#2ecc71" %)mapping(%%) the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] IM model [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] to the model [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] that [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] can manipulate{{footnote}}In this chapter, in order to distinguish VTL and SDMX model artefacts, the VTL ones are written in the Arial font while the SDMX ones in Courier New{{/footnote}}. Thus, the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] can be used in [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] as inputs and/or outputs of Transformations. It is important to be aware that the [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] do not always have the same names in the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] and [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] IMs, nor do they always have the same meaning. The more evident example is given by the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Dataset>>doc:xwiki:Glossary.Data set.WebHome]] and the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Data Set>>doc:xwiki:Glossary.Data set.WebHome]]", which do not correspond one another: as a matter of fact, the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Data Set>>doc:xwiki:Glossary.Data set.WebHome]] (% style="color:#2ecc71" %)maps(%%) to the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]]", while the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Dataset>>doc:xwiki:Glossary.Data set.WebHome]] has no explicit (% style="color:#2ecc71" %)mapping(%%) to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] (such an abstraction is not needed in the definition of [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformations). A [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Dataset>>doc:xwiki:Glossary.Data set.WebHome]]", however, is an instance of a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] and can be the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] on which the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] transformations are executed (i.e., the Transformations are defined on [[Dataflows>>doc:xwiki:Glossary.Dataflow.WebHome]] and are applied to [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] instances that can be Datasets).
++The VTL language can be applied to SDMX artefacts by mapping the SDMX IM model artefacts to the model artefacts that VTL can manipulate{{footnote}}In this chapter, in order to distinguish VTL and SDMX model artefacts, the VTL ones are written in the Arial font while the SDMX ones in Courier New{{/footnote}}. Thus, the SDMX artefacts can be used in VTL as inputs and/or outputs of Transformations. It is important to be aware that the artefacts do not always have the same names in the SDMX and VTL IMs, nor do they always have the same meaning. The more evident example is given by the SDMX Dataset and the VTL "Data Set", which do not correspond one another: as a matter of fact, the VTL "Data Set" maps to the SDMX "Dataflow", while the SDMX "Dataset" has no explicit mapping to VTL (such an abstraction is not needed in the definition of VTL Transformations). A SDMX "Dataset", however, is an instance of a SDMX "Dataflow" and can be the artefact on which the VTL transformations are executed (i.e., the Transformations are defined on Dataflows and are applied to Dataflow instances that can be Datasets).
--The [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] programs (Transformation Schemes) are represented in [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] through the TransformationScheme maintainable class which is composed of Transformation ([[nameable artefact>>doc:xwiki:Glossary.Nameable artefact.WebHome]]). Each Transformation assigns the outcome of the evaluation of a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] expression to a result.
++The VTL programs (Transformation Schemes) are represented in SDMX through the TransformationScheme maintainable class which is composed of Transformation (nameable artefact). Each Transformation assigns the outcome of the evaluation of a VTL expression to a result.
--This section does not explain the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] language or any of the content published in the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] guides. Rather, this is a description of how the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] can be used in the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] context and applied to [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]].
++This section does not explain the VTL language or any of the content published in the VTL guides. Rather, this is a description of how the VTL can be used in the SDMX context and applied to SDMX artefacts.
  == 12.2 References to SDMX artefacts from VTL statements ==
  === 12.2.1 Introduction ===
--The [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] can manipulate [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] (or objects) by referencing them through predefined conventional names (aliases).
++The VTL can manipulate SDMX artefacts (or objects) by referencing them through predefined conventional names (aliases).
--The alias of an [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] can be its URN (Universal Resource Name), an abbreviation of its URN or another user-defined name.
++The alias of an SDMX artefact can be its URN (Universal Resource Name), an abbreviation of its URN or another user-defined name.
--In any case, the aliases used in the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformations have to be (% style="color:#2ecc71" %)mapped(%%) to the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] through the VtlMappingScheme and VtlMapping classes (see the section of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] IM relevant to the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]]). A VtlMapping allows specifying the aliases to be used in the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformations, Rulesets{{footnote}}See also the section "VTL-DL Rulesets" in the VTL Reference Manual.{{/footnote}} or User Defined Operators{{footnote}}The VTLMappings are used also for User Defined Operators (UDO). Although UDOs are envisaged to be defined on generic operands, so that the specific artefacts to be manipulated are passed as parameters at their invocation, it is also possible that an UDO invokes directly some specific SDMX artefacts. These SDMX artefacts have to be mapped to the corresponding aliases used in the definition of the UDO through the VtlMappingScheme and VtlMapping classes as well.{{/footnote}} to reference [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]]. A VtlMappingScheme is a container for zero or more VtlMapping.
++In any case, the aliases used in the VTL Transformations have to be mapped to the SDMX artefacts through the VtlMappingScheme and VtlMapping classes (see the section of the SDMX IM relevant to the VTL). A VtlMapping allows specifying the aliases to be used in the VTL Transformations, Rulesets{{footnote}}See also the section "VTL-DL Rulesets" in the VTL Reference Manual.{{/footnote}} or User Defined Operators{{footnote}}The VTLMappings are used also for User Defined Operators (UDO). Although UDOs are envisaged to be defined on generic operands, so that the specific artefacts to be manipulated are passed as parameters at their invocation, it is also possible that an UDO invokes directly some specific SDMX artefacts. These SDMX artefacts have to be mapped to the corresponding aliases used in the definition of the UDO through the VtlMappingScheme and VtlMapping classes as well.{{/footnote}} to reference SDMX artefacts. A VtlMappingScheme is a container for zero or more VtlMapping.
--The correspondence between an alias and a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] must be one-to-one, meaning that a generic alias identifies one and just one [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] while a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is identified by one and just one alias. In other words, within a VtlMappingScheme an [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] can have just one alias and different [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] cannot have the same alias.
++The correspondence between an alias and a SDMX artefact must be one-to-one, meaning that a generic alias identifies one and just one SDMX artefact while a SDMX artefact is identified by one and just one alias. In other words, within a VtlMappingScheme an artefact can have just one alias and different artefacts cannot have the same alias.
  The references through the URN and the abbreviated URN are described in the following paragraphs.
  === 12.2.2 References through the URN ===
--This approach has the advantage that in the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] code the URN of the referenced [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] is directly intelligible by a human reader but has the drawback that the references are verbose.
++This approach has the advantage that in the VTL code the URN of the referenced artefacts is directly intelligible by a human reader but has the drawback that the references are verbose.
--The [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] URN{{footnote}}For a complete description of the structure of the URN see the SDMX 2.1 Standards - Section 5 - Registry Specifications, paragraph 6.2.2 ("Universal Resource Name (URN)").{{/footnote}} is the concatenation of the following parts, separated by special symbols like dot, equal, asterisk, comma, and parenthesis:
++The SDMX URN{{footnote}}For a complete description of the structure of the URN see the SDMX 2.1 Standards - Section 5 - Registry Specifications, paragraph 6.2.2 ("Universal Resource Name (URN)").{{/footnote}} is the concatenation of the following parts, separated by special symbols like dot, equal, asterisk, comma, and parenthesis:
  * SDMXprefix
--* [[SDMX-IM>>doc:xwiki:Glossary.SDMX Information Model.WebHome]]-package-name
++* SDMX-IM-package-name
  * class-name
  * agency-id
  * maintainedobject-id
--* maintainedobject-(% style="color:#2ecc71" %)version
++* maintainedobject-version
  * container-object-id{{footnote}}The container-object-id can repeat and may not be present.{{/footnote}}
  * object-id
  The generic structure of the URN is the following:
--SDMXprefix.[[SDMX-IM>>doc:xwiki:Glossary.SDMX Information Model.WebHome]]-package-name.class-name=agency-id:maintainedobject-id (maintainedobject-(% style="color:#2ecc71" %)version(%%)).*container-object-id.object-id
++SDMXprefix.SDMX-IM-package-name.class-name=agency-id:maintainedobject-id (maintainedobject-version).*container-object-id.object-id
--The **SDMXprefix** is "urn:[[sdmx>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]]:org", always the same for all [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]].
++The **SDMXprefix** is "urn:sdmx:org", always the same for all SDMX artefacts.
--The [[SDMX-IM>>doc:xwiki:Glossary.SDMX Information Model.WebHome]]-package-name** **is the concatenation of the string** **[[sdmx>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]].infomodel." with the package-name, which the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] belongs to. For example, for referencing a [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] the [[SDMX-IM>>doc:xwiki:Glossary.SDMX Information Model.WebHome]]-package-name is [[sdmx>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]].infomodel.datastructure", because the class [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] belongs to the package "datastructure".
++The SDMX-IM-package-name** **is the concatenation of the string** **"sdmx.infomodel." with the package-name, which the artefact belongs to. For example, for referencing a Dataflow the SDMX-IM-package-name is "sdmx.infomodel.datastructure", because the class Dataflow belongs to the package "datastructure".
--The class-name is the name of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] object class, which the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] object belongs to (e.g., for referencing a [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] the class-name is [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]]"). The [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] can reference [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] that belong to the classes [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]], [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]], TimeDimension, [[Measure>>doc:xwiki:Glossary.Measure.WebHome]], DataAttribute, (% style="color:#2ecc71" %)Concept(%%), Codelist.
++The class-name is the name of the SDMX object class, which the SDMX object belongs to (e.g., for referencing a Dataflow the class-name is "Dataflow"). The VTL can reference SDMX artefacts that belong to the classes Dataflow, Dimension, TimeDimension, Measure, DataAttribute, Concept, Codelist.
--The agency-id is the acronym of the agency that owns the definition of the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]], for example for the Eurostat [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] the agency-id is "ESTAT"). The agency-id can be composite (for example AgencyA.Dept1.Unit2).
++The agency-id is the acronym of the agency that owns the definition of the artefact, for example for the Eurostat artefacts the agency-id is "ESTAT"). The agency-id can be composite (for example AgencyA.Dept1.Unit2).
--The maintainedobject-id is the name of the maintained object which the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] belongs to, and in case the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] itself is maintainable{{footnote}}i.e., the artefact belongs to a maintainable class{{/footnote}}, coincides with the name of the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]]. Therefore the maintainedobject-id depends on the class of the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]]:
++The maintainedobject-id is the name of the maintained object which the artefact belongs to, and in case the artefact itself is maintainable{{footnote}}i.e., the artefact belongs to a maintainable class{{/footnote}}, coincides with the name of the artefact. Therefore the maintainedobject-id depends on the class of the artefact:
--* if the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is a [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]], which is a maintainable class, the maintainedobject-id is the [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] name ([[dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]]-id);
--* if the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is a [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]], [[Measure>>doc:xwiki:Glossary.Measure.WebHome]], TimeDimension or DataAttribute, which are not maintainable and belong to the DataStructure maintainable class, the maintainedobject-id is the name of the DataStructure (dataStructure-id) which the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] belongs to;
--* if the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is a (% style="color:#2ecc71" %)Concept(%%), which is not maintainable and belongs to the ConceptScheme maintainable class, the maintainedobject-id is the name of the ConceptScheme (conceptScheme-id) which the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] belongs to;
--* if the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is a Codelist, which is a maintainable class, the maintainedobject-id is the Codelist name (codelist-id).
++* if the artefact is a Dataflow, which is a maintainable class, the maintainedobject-id is the Dataflow name (dataflow-id);
++* if the artefact is a Dimension, Measure, TimeDimension or DataAttribute, which are not maintainable and belong to the DataStructure maintainable class, the maintainedobject-id is the name of the DataStructure (dataStructure-id) which the artefact belongs to;
++* if the artefact is a Concept, which is not maintainable and belongs to the ConceptScheme maintainable class, the maintainedobject-id is the name of the ConceptScheme (conceptScheme-id) which the artefact belongs to;
++* if the artefact is a Codelist, which is a maintainable class, the maintainedobject-id is the Codelist name (codelist-id).
--The maintainedobject-(% style="color:#2ecc71" %)version(%%) is the (% style="color:#2ecc71" %)version(%%), according to the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] versioning rules, of the maintained object which the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] belongs to (for example, possible (% style="color:#2ecc71" %)versions(%%) might be 1.0, 2.3, 1.0.0, 2.1.0 or 3.1.2).
++The maintainedobject-version is the version, according to the SDMX versioning rules, of the maintained object which the artefact belongs to (for example, possible versions might be 1.0, 2.3, 1.0.0, 2.1.0 or 3.1.2).
--The container-object-id does not apply to the classes that can be referenced in [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformations, therefore is not present in their URN
++The container-object-id does not apply to the classes that can be referenced in VTL Transformations, therefore is not present in their URN
--The object-id is the name of the non-[[maintainable artefact>>doc:xwiki:Glossary.Maintainable artefact.WebHome]] (when the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is maintainable its name is already specified as the maintainedobject-id, see above), in particular it has to be specified:
++The object-id is the name of the non-maintainable artefact (when the artefact is maintainable its name is already specified as the maintainedobject-id, see above), in particular it has to be specified:
--* if the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is a [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]], TimeDimension, [[Measure>>doc:xwiki:Glossary.Measure.WebHome]] or DataAttribute (the object-id is the name of one of the [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] above, which are data structure [[components>>doc:xwiki:Glossary.Component.WebHome]])
--* if the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is a (% style="color:#2ecc71" %)Concept(%%) (the object-id is the name of the (% style="color:#2ecc71" %)Concept(%%))
++* if the artefact is a Dimension, TimeDimension, Measure or DataAttribute (the object-id is the name of one of the artefacts above, which are data structure components)
++* if the artefact is a Concept (the object-id is the name of the Concept)
--For example, by using the URN, the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformation that sums two [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Dataflows>>doc:xwiki:Glossary.Dataflow.WebHome]] DF1 and DF2 and assigns the result to a third persistent [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] DFR, assuming that DF1, DF2 and DFR are the maintainedobject-id of the three [[Dataflows>>doc:xwiki:Glossary.Dataflow.WebHome]], that their (% style="color:#2ecc71" %)version(%%) is 1.0.0 and their Agency is AG, would be written as{{footnote}}Since these references to SDMX objects include non-permitted characters as per the VTL ID notation, they need to be included between single quotes, according to the VTL rules for irregular names.{{/footnote}}:
++For example, by using the URN, the VTL Transformation that sums two SDMX Dataflows DF1 and DF2 and assigns the result to a third persistent Dataflow DFR, assuming that DF1, DF2 and DFR are the maintainedobject-id of the three Dataflows, that their version is 1.0.0 and their Agency is AG, would be written as{{footnote}}Since these references to SDMX objects include non-permitted characters as per the VTL ID notation, they need to be included between single quotes, according to the VTL rules for irregular names.{{/footnote}}:
  'urn:sdmx:org.sdmx.infomodel.datastructure.Dataflow=AG:DFR(1.0.0)' <-
  'urn:sdmx:org.sdmx.infomodel.datastructure.Dataflow=AG:DF1(1.0.0)' +
@@ -83,20 +83,20 @@
  === 12.2.3 Abbreviation of the URN ===
--The complete formulation of the URN described above is exhaustive but verbose, even for very simple statements. In order to reduce the verbosity through a simplified identifier and make the work of transformation definers easier, proper abbreviations of the URN are possible. Using this approach, the referenced [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] remain intelligible in the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] code by a human reader.
++The complete formulation of the URN described above is exhaustive but verbose, even for very simple statements. In order to reduce the verbosity through a simplified identifier and make the work of transformation definers easier, proper abbreviations of the URN are possible. Using this approach, the referenced artefacts remain intelligible in the VTL code by a human reader.
--The URN can be abbreviated by omitting the parts that are not essential for the identification of the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] or that can be deduced from other available information, including the context in which the invocation is made. The possible abbreviations are described below.
++The URN can be abbreviated by omitting the parts that are not essential for the identification of the artefact or that can be deduced from other available information, including the context in which the invocation is made. The possible abbreviations are described below.
--* The SDMXprefix can be omitted for all the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] objects, because it is a prefixed string (urn:[[sdmx>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]]:org), always the same for [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] objects. • The [[SDMX-IM>>doc:xwiki:Glossary.SDMX Information Model.WebHome]]-package-name** **can be omitted as well because it can be deduced from the class-name that follows it (the table of the [[SDMX-IM>>doc:xwiki:Glossary.SDMX Information Model.WebHome]] packages and classes that allows this deduction is in the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] 2.1 Standards - Section 5 - Registry Specifications, paragraph 6.2.3). In particular, considering the object classes of the [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] that [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] can reference, the package is:
--** "datastructure" for the classes [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]], [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]], TimeDimension, [[Measure>>doc:xwiki:Glossary.Measure.WebHome]], DataAttribute, o "conceptscheme" for the class (% style="color:#2ecc71" %)Concept(%%), o "codelist" for the class Codelist.
--* The class-name can be omitted as it can be deduced from the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] invocation. In particular, starting from the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] class of the invoked [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] (e.g. [[dataset>>doc:xwiki:Glossary.Data set.WebHome]], [[component>>doc:xwiki:Glossary.Component.WebHome]], identifier, [[measure>>doc:xwiki:Glossary.Measure.WebHome]], [[attribute>>doc:xwiki:Glossary.Attribute.WebHome]], variable, valuedomain), which is known given the syntax of the invoking [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] operator{{footnote}}For the syntax of the VTL operators see the VTL Reference Manual{{/footnote}}, the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] class can be deduced from the (% style="color:#2ecc71" %)mapping(%%) rules between [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] and [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] (see the section (% style="color:#2ecc71" %)Mapping(%%) between [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] and [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] hereinafter){{footnote}}In case the invoked artefact is a VTL component, which can be invoked only within the invocation of a VTL data set (SDMX Dataflow), the specific SDMX class-name (e.g. Dimension, TimeDimension, Measure or DataAttribute) can be deduced from the data structure of the SDMX Dataflow, which the component belongs to.{{/footnote}}.
--* If the agency-id is not specified, it is assumed by default equal to the agency-id of the TransformationScheme, UserDefinedOperatorScheme or RulesetScheme from which the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is invoked. For example, the agencyid can be omitted if it is the same as the invoking TransformationScheme and cannot be omitted if the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] comes from another agency{{footnote}}If the Agency is composite (for example AgencyA.Dept1.Unit2), the agency is considered different even if only part of the composite name is different (for example AgencyA.Dept1.Unit3 is a different Agency than the previous one). Moreover the agency-id cannot be omitted in part (i.e., if a TransformationScheme owned by AgencyA.Dept1.Unit2 references an artefact coming from AgencyA.Dept1.Unit3, the specification of the agency-id becomes mandatory and must be complete, without omitting the possibly equal parts like AgencyA.Dept1){{/footnote}}. Take also into account that, according to the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] consistency rules, the agency of the result of a Transformation must be the same as its TransformationScheme, therefore the agency-id can be omitted for all the results (left part of Transformation statements).
--* As for the maintainedobject-id, this is essential in some cases while in other cases it can be omitted: o if the referenced [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is a [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]], which is a maintainable class, the maintainedobject-id is the [[dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]]-id and obviously cannot be omitted;
--** if the referenced [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is a [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]], TimeDimension, [[Measure>>doc:xwiki:Glossary.Measure.WebHome]], DataAttribute, which are not maintainable and belong to the DataStructure maintainable class, the maintainedobject-id is the dataStructure-id and can be omitted, given that these [[components>>doc:xwiki:Glossary.Component.WebHome]] are always invoked within the invocation of a [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]], whose dataStructure-id can be deduced from the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] structural definitions;
--** if the referenced [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is a (% style="color:#2ecc71" %)Concept(%%), which is not maintainable and belong to the ConceptScheme maintainable class, the maintained object is the conceptScheme-id and cannot be omitted;
--** if the referenced [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] is a Codelist, which is a maintainable class, the maintainedobject-id is the codelist-id and obviously cannot be omitted.
--* When the maintainedobject-id is omitted, the maintainedobject-(% style="color:#2ecc71" %)version(%%) is omitted too. When the maintainedobject-id is not omitted and the maintainedobject-(% style="color:#2ecc71" %)version(%%) is omitted, the (% style="color:#2ecc71" %)version(%%) 1.0 is assumed by default. • As said, the container-object-id does not apply to the classes that can be referenced in [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformations, therefore is not present in their URN
--* The object-id does not exist for the [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] belonging to the [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]], and Codelist classes, while it exists and cannot be omitted for the [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] belonging to the classes [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]], TimeDimension, [[Measure>>doc:xwiki:Glossary.Measure.WebHome]], DataAttribute and (% style="color:#2ecc71" %)Concept(%%), as for them the object-id is the main identifier of the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]]
++* The SDMXprefix can be omitted for all the SDMX objects, because it is a prefixed string (urn:sdmx:org), always the same for SDMX objects. • The SDMX-IM-package-name** **can be omitted as well because it can be deduced from the class-name that follows it (the table of the SDMX-IM packages and classes that allows this deduction is in the SDMX 2.1 Standards - Section 5 - Registry Specifications, paragraph 6.2.3). In particular, considering the object classes of the artefacts that VTL can reference, the package is:
++** "datastructure" for the classes Dataflow, Dimension, TimeDimension, Measure, DataAttribute, o "conceptscheme" for the class Concept, o "codelist" for the class Codelist.
++* The class-name can be omitted as it can be deduced from the VTL invocation. In particular, starting from the VTL class of the invoked artefact (e.g. dataset, component, identifier, measure, attribute, variable, valuedomain), which is known given the syntax of the invoking VTL operator{{footnote}}For the syntax of the VTL operators see the VTL Reference Manual{{/footnote}}, the SDMX class can be deduced from the mapping rules between VTL and SDMX (see the section "Mapping between VTL and SDMX" hereinafter){{footnote}}In case the invoked artefact is a VTL component, which can be invoked only within the invocation of a VTL data set (SDMX Dataflow), the specific SDMX class-name (e.g. Dimension, TimeDimension, Measure or DataAttribute) can be deduced from the data structure of the SDMX Dataflow, which the component belongs to.{{/footnote}}.
++* If the agency-id is not specified, it is assumed by default equal to the agency-id of the TransformationScheme, UserDefinedOperatorScheme or RulesetScheme from which the artefact is invoked. For example, the agencyid can be omitted if it is the same as the invoking TransformationScheme and cannot be omitted if the artefact comes from another agency{{footnote}}If the Agency is composite (for example AgencyA.Dept1.Unit2), the agency is considered different even if only part of the composite name is different (for example AgencyA.Dept1.Unit3 is a different Agency than the previous one). Moreover the agency-id cannot be omitted in part (i.e., if a TransformationScheme owned by AgencyA.Dept1.Unit2 references an artefact coming from AgencyA.Dept1.Unit3, the specification of the agency-id becomes mandatory and must be complete, without omitting the possibly equal parts like AgencyA.Dept1){{/footnote}}. Take also into account that, according to the VTL consistency rules, the agency of the result of a Transformation must be the same as its TransformationScheme, therefore the agency-id can be omitted for all the results (left part of Transformation statements).
++* As for the maintainedobject-id, this is essential in some cases while in other cases it can be omitted: o if the referenced artefact is a Dataflow, which is a maintainable class, the maintainedobject-id is the dataflow-id and obviously cannot be omitted;
++** if the referenced artefact is a Dimension, TimeDimension, Measure, DataAttribute, which are not maintainable and belong to the DataStructure maintainable class, the maintainedobject-id is the dataStructure-id and can be omitted, given that these components are always invoked within the invocation of a Dataflow, whose dataStructure-id can be deduced from the SDMX structural definitions;
++** if the referenced artefact is a Concept, which is not maintainable and belong to the ConceptScheme maintainable class, the maintained object is the conceptScheme-id and cannot be omitted;
++** if the referenced artefact is a Codelist, which is a maintainable class, the maintainedobject-id is the codelist-id and obviously cannot be omitted.
++* When the maintainedobject-id is omitted, the maintainedobject-version is omitted too. When the maintainedobject-id is not omitted and the maintainedobject-version is omitted, the version 1.0 is assumed by default. • As said, the container-object-id does not apply to the classes that can be referenced in VTL Transformations, therefore is not present in their URN
++* The object-id does not exist for the artefacts belonging to the Dataflow, and Codelist classes, while it exists and cannot be omitted for the artefacts belonging to the classes Dimension, TimeDimension, Measure, DataAttribute and Concept, as for them the object-id is the main identifier of the artefact
  The simplified object identifier is obtained by omitting all the first part of the URN, including the special characters, till the first part not omitted.
@@ -118,7 +118,7 @@
  CL_FREQ
--As for the references to the [[components>>doc:xwiki:Glossary.Component.WebHome]], it can be enough to specify the componentId, given that the dataStructure-Id can be omitted. An example of non-abbreviated reference, if the data structure is DST1 and the [[component>>doc:xwiki:Glossary.Component.WebHome]] is SECTOR, is the following:
++As for the references to the components, it can be enough to specify the componentId, given that the dataStructure-Id can be omitted. An example of non-abbreviated reference, if the data structure is DST1 and the component is SECTOR, is the following:
  'urn:sdmx:org.sdmx.infomodel.datastructure.DataStructure=AG:DST1(1.0.0).S
@@ -128,13 +128,13 @@
  SECTOR
--For example, the Transformation for renaming the [[component>>doc:xwiki:Glossary.Component.WebHome]] SECTOR of the [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] DF1 into SEC can be written as{{footnote}}The result DFR(1.0.0) is be equal to DF1(1.0.0) save that the component SECTOR is called SEC{{/footnote}}:
++For example, the Transformation for renaming the component SECTOR of the Dataflow DF1 into SEC can be written as{{footnote}}The result DFR(1.0.0) is be equal to DF1(1.0.0) save that the component SECTOR is called SEC{{/footnote}}:
  'DFR(1.0.0)' := 'DF1(1.0.0)' [rename SECTOR to SEC]
--In the references to the (% style="color:#2ecc71" %)Concepts(%%), which can exist for example in the definition of the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Rulesets, at least the conceptScheme-id and the (% style="color:#2ecc71" %)concept(%%)-id must be specified.
++In the references to the Concepts, which can exist for example in the definition of the VTL Rulesets, at least the conceptScheme-id and the concept-id must be specified.
--An example of non-abbreviated reference, if the conceptScheme-id is CS1 and the (% style="color:#2ecc71" %)concept(%%)-id is SECTOR, is the following:
++An example of non-abbreviated reference, if the conceptScheme-id is CS1 and the concept-id is SECTOR, is the following:
  'urn:sdmx:org.sdmx.infomodel.conceptscheme.Concept=AG:CS1(1.0.0).SECTOR'
@@ -142,57 +142,57 @@
  CS1(1.0.0).SECTOR
--The [[Codes>>doc:xwiki:Glossary.Code.WebHome]] and in general all the Values can be written without any other specification, for example, the transformation to check if the values of the [[measures>>doc:xwiki:Glossary.Measure.WebHome]] of the [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] DF1 are between 0 and 25000 can be written like follows:
++The Codes and in general all the Values can be written without any other specification, for example, the transformation to check if the values of the measures of the Dataflow DF1 are between 0 and 25000 can be written like follows:
  'DFR(1.0.0)' := between ( 'DF1(1.0.0)', 0, 25000 )
--The [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] ([[Component>>doc:xwiki:Glossary.Component.WebHome]], (% style="color:#2ecc71" %)Concept(%%), Codelist …) which the Values are referred to can be deduced from the context in which the reference is made, taking also into account the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] syntax. In the Transformation above, for example, the values 0 and 2500 are compared to the values of the [[measures>>doc:xwiki:Glossary.Measure.WebHome]] of DF1(1.0.0).
++The artefact (Component, Concept, Codelist …) which the Values are referred to can be deduced from the context in which the reference is made, taking also into account the VTL syntax. In the Transformation above, for example, the values 0 and 2500 are compared to the values of the measures of DF1(1.0.0).
  === 12.2.4 User-defined alias ===
--The third possibility for referencing [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] from [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] statements is to use user-defined aliases not related to the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] URN of the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]].
++The third possibility for referencing SDMX artefacts from VTL statements is to use user-defined aliases not related to the SDMX URN of the artefact.
--This approach gives preference to the use of symbolic names for the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]]. As a consequence, in the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] code the referenced [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] may become not directly intelligible by a human reader. In any case, the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] aliases are associated to the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] URN through the VtlMappingScheme and VtlMapping classes. These classes provide for structured references to [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] whatever kind of reference is used in [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] statements (URN, abbreviated URN or user-defined aliases).
++This approach gives preference to the use of symbolic names for the SDMX artefacts. As a consequence, in the VTL code the referenced artefacts may become not directly intelligible by a human reader. In any case, the VTL aliases are associated to the SDMX URN through the VtlMappingScheme and VtlMapping classes. These classes provide for structured references to SDMX artefacts whatever kind of reference is used in VTL statements (URN, abbreviated URN or user-defined aliases).
  === 12.2.5 References to SDMX artefacts from VTL Rulesets ===
--The [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Rulesets allow defining sets of reusable Rules that can be applied by some [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] operators, like the ones for validation and hierarchical roll-up. A "Rule" consists in a relationship between Values belonging to some Value Domains or taken by some Variables, for example: when the Country is USA then the [[Currency>>doc:xwiki:Glossary.Currency.WebHome]] is USD; (ii) the Benelux is composed by Belgium, Luxembourg, Netherlands.
++The VTL Rulesets allow defining sets of reusable Rules that can be applied by some VTL operators, like the ones for validation and hierarchical roll-up. A "Rule" consists in a relationship between Values belonging to some Value Domains or taken by some Variables, for example: (i) when the Country is USA then the Currency is USD; (ii) the Benelux is composed by Belgium, Luxembourg, Netherlands.
--The [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Rulesets have a signature, in which the Value Domains or the Variables on which the Ruleset is defined are declared, and a body, which contains the Rules.
++The VTL Rulesets have a signature, in which the Value Domains or the Variables on which the Ruleset is defined are declared, and a body, which contains the Rules.
--In the signature, given the mapping between [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] and [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] better described in the following paragraphs, a reference to a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Value Domain becomes a reference to a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] Codelist, while a reference to a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Represented Variable becomes a reference to a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] (% style="color:#2ecc71" %)Concept(%%), assuming for it a definite representation{{footnote}}Rulesets of this kind cannot be reused when the referenced Concept has a different representation.{{/footnote}}.
++In the signature, given the mapping between VTL and SDMX better described in the following paragraphs, a reference to a VTL Value Domain becomes a reference to a SDMX Codelist, while a reference to a VTL Represented Variable becomes a reference to a SDMX Concept, assuming for it a definite representation{{footnote}}Rulesets of this kind cannot be reused when the referenced Concept has a different representation.{{/footnote}}.
--In general, for referencing [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] Codelists and (% style="color:#2ecc71" %)Concepts(%%), the conventions described in the previous paragraphs apply. In the Ruleset syntax, the elements that reference [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] are called "valueDomain" and "variable" for the Datapoint Rulesets and "ruleValueDomain", "ruleVariable", "condValueDomain" "condVariable" for the Hierarchical Rulesets). The syntax of the Ruleset signature allows also to define aliases of the elements above, these aliases are valid only within the specific Ruleset definition statement and cannot be (% style="color:#2ecc71" %)mapped(%%) to [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]].{{footnote}}See also the section "VTL-DL Rulesets" in the VTL Reference Manual.{{/footnote}}
++In general, for referencing SDMX Codelists and Concepts, the conventions described in the previous paragraphs apply. In the Ruleset syntax, the elements that reference SDMX artefacts are called "valueDomain" and "variable" for the Datapoint Rulesets and "ruleValueDomain", "ruleVariable", "condValueDomain" "condVariable" for the Hierarchical Rulesets). The syntax of the Ruleset signature allows also to define aliases of the elements above, these aliases are valid only within the specific Ruleset definition statement and cannot be mapped to SDMX.{{footnote}}See also the section "VTL-DL Rulesets" in the VTL Reference Manual.{{/footnote}}
--In the body of the Rulesets, the [[Codes>>doc:xwiki:Glossary.Code.WebHome]] and in general all the Values can be written without any other specification, because the [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]], which the Values are referred (Codelist, (% style="color:#2ecc71" %)Concept(%%)) to can be deduced from the Ruleset signature.
++In the body of the Rulesets, the Codes and in general all the Values can be written without any other specification, because the artefact, which the Values are referred (Codelist, Concept) to can be deduced from the Ruleset signature.
  == 12.3 Mapping between SDMX and VTL artefacts ==
  === 12.3.1 When the mapping occurs ===
--The mapping methods between the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] and [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] object classes allow transforming a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] definition in a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] one and vice-versa for the [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]] to be manipulated. It should be remembered that [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] programs (i.e. Transformation Schemes) are represented in [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] through the TransformationScheme maintainable class which is composed of Transformations ([[nameable artefacts>>doc:xwiki:Glossary.Nameable artefact.WebHome]]). Each Transformation assigns the outcome of the evaluation of a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] expression to a result: the input operands of the expression and the result can be [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:xwiki:Glossary.Artefact.WebHome]].
++The mapping methods between the VTL and SDMX object classes allow transforming a SDMX definition in a VTL one and vice-versa for the artefacts to be manipulated. It should be remembered that VTL programs (i.e. Transformation Schemes) are represented in SDMX through the TransformationScheme maintainable class which is composed of Transformations (nameable artefacts). Each Transformation assigns the outcome of the evaluation of a VTL expression to a result: the input operands of the expression and the result can be SDMX artefacts.
--Every time a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] object is referenced in a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformation as an input operand, there is the need to generate a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] definition of the object, so that the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] operations can take place. This can be made starting from the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] definition and applying a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]]-[[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] mapping method in the direction from [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]]. The possible mapping methods from [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] are described in the following paragraphs and are conceived to allow the automatic deduction of the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] definition of the object from the knowledge of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] definition.
++Every time a SDMX object is referenced in a VTL Transformation as an input operand, there is the need to generate a VTL definition of the object, so that the VTL operations can take place. This can be made starting from the SDMX definition and applying a SDMX-VTL mapping method in the direction from SDMX to VTL. The possible mapping methods from SDMX to VTL are described in the following paragraphs and are conceived to allow the automatic deduction of the VTL definition of the object from the knowledge of the SDMX definition.
--In the opposite direction, every time an object calculated by means of [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] must be treated as a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] object (for example for exchanging it through [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]]), there is the need of a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] definition of the object, so that the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] operations can take place. The [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] definition is needed for the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] objects for which a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] use is envisaged{{footnote}}If a calculated artefact is persistent, it needs a persistent definition, i.e. a SDMX definition in a SDMX environment. In addition, possible calculated artefact that are not persistent may require a SDMX definition, for example when the result of a non-persistent calculation is disseminated through SDMX tools (like an inquiry tool).{{/footnote}}.
++In the opposite direction, every time an object calculated by means of VTL must be treated as a SDMX object (for example for exchanging it through SDMX), there is the need of a SDMX definition of the object, so that the SDMX operations can take place. The SDMX definition is needed for the VTL objects for which a SDMX use is envisaged{{footnote}}If a calculated artefact is persistent, it needs a persistent definition, i.e. a SDMX definition in a SDMX environment. In addition, possible calculated artefact that are not persistent may require a SDMX definition, for example when the result of a non-persistent calculation is disseminated through SDMX tools (like an inquiry tool).{{/footnote}}.
--The mapping methods from [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] to [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] are described in the following paragraphs as well, however they do not allow the complete [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] definition to be automatically deduced from the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] definition, more than all because the former typically contains additional information in respect to the latter. For example, the definition of a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[DSD>>doc:xwiki:Glossary.Data structure definition.WebHome]] includes also some mandatory information not available in [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] (like the [[concept scheme>>doc:xwiki:Glossary.Concept scheme.WebHome]] to which the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[components>>doc:xwiki:Glossary.Component.WebHome]] refer, the ‘usage’ and ‘attributeRelationship’ for the DataAttributes and so on). Therefore the mapping methods from [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] to [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] provide only a general guidance for generating [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] definitions properly starting from the information available in [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]], independently of how the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] definition it is actually generated (manually, automatically or part and part).
++The mapping methods from VTL to SDMX are described in the following paragraphs as well, however they do not allow the complete SDMX definition to be automatically deduced from the VTL definition, more than all because the former typically contains additional information in respect to the latter. For example, the definition of a SDMX DSD includes also some mandatory information not available in VTL (like the concept scheme to which the SDMX components refer, the ‘usage’ and ‘attributeRelationship’ for the DataAttributes and so on). Therefore the mapping methods from VTL to SDMX provide only a general guidance for generating SDMX definitions properly starting from the information available in VTL, independently of how the SDMX definition it is actually generated (manually, automatically or part and part).
  === 12.3.2 General mapping of VTL and SDMX data structures ===
--This section makes reference to the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] "Model for data and their structure"{{footnote}}See the VTL 2.0 User Manual{{/footnote}} and the correspondent [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] "Data Structure Definition"{{footnote}}See the SDMX Standards Section 2 – Information Model{{/footnote}}.
++This section makes reference to the VTL "Model for data and their structure"{{footnote}}See the VTL 2.0 User Manual{{/footnote}} and the correspondent SDMX "Data Structure Definition"{{footnote}}See the SDMX Standards Section 2 – Information Model{{/footnote}}.
--The main type of [[artefact>>doc:xwiki:Glossary.Artefact.WebHome]] that the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] can manipulate is the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Data Set>>doc:xwiki:Glossary.Data set.WebHome]], which in general is (% style="color:#2ecc71" %)mapped(%%) to the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]]. This means that a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformation, in the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] context, expresses the algorithm for calculating a derived [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] starting from some already existing [[Dataflows>>doc:xwiki:Glossary.Dataflow.WebHome]] (either collected or derived).{{footnote}}Besides the mapping between one SDMX Dataflow and one VTL Data Set, it is also possible to map distinct parts of a SDMX Dataflow to different VTL Data Set, as explained in a following paragraph.{{/footnote}}
++The main type of artefact that the VTL can manipulate is the VTL Data Set, which in general is mapped to the SDMX Dataflow. This means that a VTL Transformation, in the SDMX context, expresses the algorithm for calculating a derived Dataflow starting from some already existing Dataflows (either collected or derived).{{footnote}}Besides the mapping between one SDMX Dataflow and one VTL Data Set, it is also possible to map distinct parts of a SDMX Dataflow to different VTL Data Set, as explained in a following paragraph.{{/footnote}}
--While the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformations are defined in term of [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] definitions, they are assumed to be executed on instances of such [[Dataflows>>doc:xwiki:Glossary.Dataflow.WebHome]], provided at runtime to the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] engine (the mechanism for identifying the instances to be processed are not part of the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] specifications and depend on the implementation of the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]]-based systems). As already said, the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Datasets>>doc:xwiki:Glossary.Data set.WebHome]] are instances of [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Dataflows>>doc:xwiki:Glossary.Dataflow.WebHome]], therefore a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Transformation defined on some [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Dataflows>>doc:xwiki:Glossary.Dataflow.WebHome]] can be applied on some corresponding [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Datasets>>doc:xwiki:Glossary.Data set.WebHome]].
++While the VTL Transformations are defined in term of Dataflow definitions, they are assumed to be executed on instances of such Dataflows, provided at runtime to the VTL engine (the mechanism for identifying the instances to be processed are not part of the VTL specifications and depend on the implementation of the VTL-based systems). As already said, the SDMX Datasets are instances of SDMX Dataflows, therefore a VTL Transformation defined on some SDMX Dataflows can be applied on some corresponding SDMX Datasets.
--A [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Data Set>>doc:xwiki:Glossary.Data set.WebHome]] is structured by one and just one Data Structure and a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Data Structure can structure any number of [[Data Sets>>doc:xwiki:Glossary.Data set.WebHome]]. Correspondingly, in the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] context a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Dataflow>>doc:xwiki:Glossary.Dataflow.WebHome]] is structured by one and just one DataStructureDefinition and one DataStructureDefinition can structure any number of [[Dataflows>>doc:xwiki:Glossary.Dataflow.WebHome]].
++A VTL Data Set is structured by one and just one Data Structure and a VTL Data Structure can structure any number of Data Sets. Correspondingly, in the SDMX context a SDMX Dataflow is structured by one and just one DataStructureDefinition and one DataStructureDefinition can structure any number of Dataflows.
--A [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Data Set>>doc:xwiki:Glossary.Data set.WebHome]] has a Data Structure made of [[Components>>doc:xwiki:Glossary.Component.WebHome]], which in turn can be Identifiers, [[Measures>>doc:xwiki:Glossary.Measure.WebHome]] and [[Attributes>>doc:xwiki:Glossary.Attribute.WebHome]]. Similarly, a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] DataflowDefinition has a DataStructureDefinition made of [[components>>doc:xwiki:Glossary.Component.WebHome]] that can be DimensionComponents, [[Measure>>doc:xwiki:Glossary.Measure.WebHome]] and DataAttributes. In turn, a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]]
++A VTL Data Set has a Data Structure made of Components, which in turn can be Identifiers, Measures and Attributes. Similarly, a SDMX DataflowDefinition has a DataStructureDefinition made of components that can be DimensionComponents, Measure and DataAttributes. In turn, a SDMX
--DimensionComponent can be a [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]] or a TimeDimension.
++DimensionComponent can be a Dimension or a TimeDimension.
--Correspondingly, in the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] implementation of the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]], the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Identifiers can be (optionally) distinguished in similar sub-classes (Simple Identifier, Time Identifier) even if such a distinction is not evidenced in the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] IM.
++Correspondingly, in the SDMX implementation of the VTL, the VTL Identifiers can be (optionally) distinguished in similar sub-classes (Simple Identifier, Time Identifier) even if such a distinction is not evidenced in the VTL IM.
  The possible mapping options are described in more detail in the following sections.
@@ -200,7 +200,7 @@
  ==== 12.3.3.1 Basic Mapping ====
--The main mapping method from [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] is called **Basic **mapping. This is considered as the default mapping method and is applied unless a different method is specified through the VtlMappingScheme and VtlDataflowMapping classes. When transforming **from [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]]**, this method consists in leaving the [[components>>doc:xwiki:Glossary.Component.WebHome]] unchanged and maintaining their names and roles, according to the following table:
++The main mapping method from SDMX to VTL is called **Basic **mapping. This is considered as the default mapping method and is applied unless a different method is specified through the VtlMappingScheme and VtlDataflowMapping classes. When transforming **from SDMX to VTL**, this method consists in leaving the components unchanged and maintaining their names and roles, according to the following table:
  (% style="width:529.294px" %)
  |(% style="width:151px" %)**SDMX**|(% style="width:375px" %)**VTL**
@@ -209,73 +209,75 @@
  |(% style="width:151px" %)Measure|(% style="width:375px" %)Measure
  |(% style="width:151px" %)DataAttribute|(% style="width:375px" %)Attribute
--The [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] DataAttributes, in [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] they are all considered "at data point / observation (% style="color:#2ecc71" %)level(%%) (i.e. dependent on all the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Identifiers), because [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] does not have the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] AttributeRelationships, which defines the construct to which the DataAttribute is related (e.g. observation, [[dimension>>doc:xwiki:Glossary.Dimension.WebHome]] or set or group of [[dimensions>>doc:xwiki:Glossary.Dimension.WebHome]], whole [[data set>>doc:xwiki:Glossary.Data set.WebHome]]).
++The SDMX DataAttributes, in VTL they are all considered "at data point / observation level" (i.e. dependent on all the VTL Identifiers), because VTL does not have the SDMX AttributeRelationships, which defines the construct to which the DataAttribute is related (e.g. observation, dimension or set or group of dimensions, whole data set).
--With the Basic mapping, one [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] observation{{footnote}}Here an SDMX observation is meant to correspond to one combination of values of the DimensionComponents.{{/footnote}} generates one [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] data point.
++With the Basic mapping, one SDMX observation{{footnote}}Here an SDMX observation is meant to correspond to one combination of values of the DimensionComponents.{{/footnote}} generates one VTL data point.
  ==== 12.3.3.2 Pivot Mapping ====
--An alternative mapping method from [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] is the **Pivot **mapping, which makes sense and is different from the Basic method only for the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] data structures that contain a [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]] that plays the role of [[measure>>doc:xwiki:Glossary.Measure.WebHome]] [[dimension>>doc:xwiki:Glossary.Dimension.WebHome]] (like in [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] 2.1) and just one [[Measure>>doc:xwiki:Glossary.Measure.WebHome]]. Through this method, these structures can be (% style="color:#2ecc71" %)mapped(%%) to multimeasure [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] data structures. Besides that, a user may choose to use any [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]] acting as a list of [[Measures>>doc:xwiki:Glossary.Measure.WebHome]] (e.g., a [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]] with indicators), either by considering the “[[Measure>>doc:xwiki:Glossary.Measure.WebHome]]” role of a [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]], or at will using any coded [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]]. Of course, in [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] 3.0, this can only work when only one [[Measure>>doc:xwiki:Glossary.Measure.WebHome]] is defined in the DSD.
++An alternative mapping method from SDMX to VTL is the **Pivot **mapping, which makes sense and is different from the Basic method only for the SDMX data structures that contain a Dimension that plays the role of measure dimension (like in SDMX 2.1) and just one Measure. Through this method, these structures can be mapped to multimeasure VTL data structures. Besides that, a user may choose to use any Dimension acting as a list of Measures (e.g., a Dimension with indicators), either by considering the “Measure” role of a Dimension, or at will using any coded Dimension. Of course, in SDMX 3.0, this can only work when only one Measure is defined in the DSD.
--In [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] 2.1 the MeasureDimension was a subclass of DimensionComponent like [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]] and TimeDimension. In the current [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] (% style="color:#2ecc71" %)version(%%), this subclass does not exist anymore, however a [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]] can have the role of [[measure>>doc:xwiki:Glossary.Measure.WebHome]] [[dimension>>doc:xwiki:Glossary.Dimension.WebHome]] (i.e. a [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]] that contributes to the identification of the [[measures>>doc:xwiki:Glossary.Measure.WebHome]]). In [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] 2.1 a DataStructure could have zero or one MeasureDimensions, in the current (% style="color:#2ecc71" %)version(%%) of the standard, from zero to many [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]] may have the role of [[measure>>doc:xwiki:Glossary.Measure.WebHome]] [[dimension>>doc:xwiki:Glossary.Dimension.WebHome]]. Hereinafter a [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]] that plays the role of [[measure>>doc:xwiki:Glossary.Measure.WebHome]] [[dimension>>doc:xwiki:Glossary.Dimension.WebHome]] is referenced for simplicity as “MeasureDimension“, i.e. maintaining the capital letters and the courier font even if the MeasureDimension is not anymore a class in the [[SDMX Information Model>>doc:xwiki:Glossary.SDMX Information Model.WebHome]] of the current [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] (% style="color:#2ecc71" %)version(%%). For the sake of simplicity, the description below considers just one [[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]] having the role of MeasureDimension (i.e., the more simple and common case). Nevertheless, it maintains its validity also if in the DataStructure there are more [[dimension>>doc:xwiki:Glossary.Dimension.WebHome]] with the role of MeasureDimensions: in this case what is said about the MeasureDimension must be applied to the combination of all the MeasureDimensions considered as a joint variable{{footnote}}E.g., if in the data structure there exist 3 Dimensions C,D,E having the role of MeasureDimension, they should be considered as a joint MeasureDimension Z=(C,D,E); therefore when the description says “each possible value Cj of the MeasureDimension …” it means “each possible combination of values (Cj, Dk, Ew) of the joint MeasureDimension Z=(C,D,E)”.{{/footnote}}.
++In SDMX 2.1 the MeasureDimension was a subclass of DimensionComponent like Dimension and TimeDimension. In the current SDMX version, this subclass does not exist anymore, however a Dimension can have the role of measure dimension (i.e. a Dimension that contributes to the identification of the measures). In SDMX 2.1 a DataStructure could have zero or one MeasureDimensions, in the current version of the standard, from zero to many Dimension may have the role of measure dimension. Hereinafter a Dimension that plays the role of measure dimension is referenced for simplicity as “MeasureDimension“, i.e. maintaining the capital letters and the courier font even if the MeasureDimension is not anymore a class in the SDMX Information Model of the current SDMX version. For the sake of simplicity, the description below considers just one Dimension having the role of MeasureDimension (i.e., the more simple and common case). Nevertheless, it maintains its validity also if in the DataStructure there are more dimension with the role of MeasureDimensions: in this case what is said about the MeasureDimension must be applied to the combination of all the MeasureDimensions considered as a joint variable{{footnote}}E.g., if in the data structure there exist 3 Dimensions C,D,E having the role of MeasureDimension, they should be considered as a joint MeasureDimension Z=(C,D,E); therefore when the description says “each possible value Cj of the MeasureDimension …” it means “each possible combination of values (Cj, Dk, Ew) of the joint MeasureDimension Z=(C,D,E)”.{{/footnote}}.
--Among other things, the Pivot method provides also backward compatibility with the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] 2.1 data structures that contained a MeasureDimension.
++Among other things, the Pivot method provides also backward compatibility with the SDMX 2.1 data structures that contained a MeasureDimension.
--If applied to [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] structures that do not contain any MeasureDimension, this method behaves like the Basic mapping (see the previous paragraph).
++If applied to SDMX structures that do not contain any MeasureDimension, this method behaves like the Basic mapping (see the previous paragraph).
--Here an [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] observation is meant to correspond to one combination of values of the DimensionComponents.
++Here an SDMX observation is meant to correspond to one combination of values of the DimensionComponents.
--The [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] structures that contain a MeasureDimension are (% style="color:#2ecc71" %)mapped(%%) as described below (this mapping is equivalent to a pivoting operation):
++The SDMX structures that contain a MeasureDimension are mapped as described below (this mapping is equivalent to a pivoting operation):
--* A [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] simple [[dimension>>doc:xwiki:Glossary.Dimension.WebHome]] becomes a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] (simple) identifier and a [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] TimeDimension becomes a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] (time) identifier;
--* Each possible [[Code>>doc:xwiki:Glossary.Code.WebHome]] Cj of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] MeasureDimension is (% style="color:#2ecc71" %)mapped(%%) to a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Measure>>doc:xwiki:Glossary.Measure.WebHome]], having the same name as the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Code>>doc:xwiki:Glossary.Code.WebHome]] (i.e. Cj); the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Measure>>doc:xwiki:Glossary.Measure.WebHome]] Cj is a new [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[component>>doc:xwiki:Glossary.Component.WebHome]] even if the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] data structure has not such a [[Component>>doc:xwiki:Glossary.Component.WebHome]];
--* The [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] MeasureDimension is not (% style="color:#2ecc71" %)mapped(%%) to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] (it disappears in the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Data Structure);
--* The [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] [[Measure>>doc:xwiki:Glossary.Measure.WebHome]] is not (% style="color:#2ecc71" %)mapped(%%) to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] as well (it disappears in the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Data Structure);
--* An [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] DataAttribute is (% style="color:#2ecc71" %)mapped(%%) in different ways according to its AttributeRelationship:
--** If, according to the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] AttributeRelationship, the values of the DataAttribute do not depend on the values of the MeasureDimension, the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] DataAttribute becomes a [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Attribute>>doc:xwiki:Glossary.Attribute.WebHome]] having the same name. This happens if the AttributeRelationship is not specified (i.e. the DataAttribute does not depend on any DimensionComponent and therefore is at [[data set>>doc:xwiki:Glossary.Data set.WebHome]] (% style="color:#2ecc71" %)level(%%)), or if it refers to a set (or a group) of [[dimensions>>doc:xwiki:Glossary.Dimension.WebHome]] which does not include the MeasureDimension;
--** Otherwise, if, according to the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] AttributeRelationship, the values of the DataAttribute depend on the MeasureDimension, the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] DataAttribute is (% style="color:#2ecc71" %)mapped(%%) to one [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Attribute>>doc:xwiki:Glossary.Attribute.WebHome]] for each possible [[Code>>doc:xwiki:Glossary.Code.WebHome]] of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] MeasureDimension. By default, the names of the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Attributes>>doc:xwiki:Glossary.Attribute.WebHome]] are obtained by concatenating the name of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] DataAttribute and the names of the correspondent [[Code>>doc:xwiki:Glossary.Code.WebHome]] of the MeasureDimension separated by underscore. For example, if the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] DataAttribute is named DA and the possible [[Codes>>doc:xwiki:Glossary.Code.WebHome]] of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] MeasureDimension are named C1, C2, …, Cn, then the corresponding [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Attributes>>doc:xwiki:Glossary.Attribute.WebHome]] will be named DA_C1, DA_C2, …, DA_Cn (if different names are desired, they can be achieved afterwards by renaming the [[Attributes>>doc:xwiki:Glossary.Attribute.WebHome]] through [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] operators).
--** Like in the Basic mapping, the resulting [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Attributes>>doc:xwiki:Glossary.Attribute.WebHome]] are considered as dependent on all the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] identifiers (i.e. "at data point / observation (% style="color:#2ecc71" %)level(%%)"), because [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] does not have the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] notion of [[Attribute>>doc:xwiki:Glossary.Attribute.WebHome]] Relationship.
++* A SDMX simple dimension becomes a VTL (simple) identifier and a SDMX TimeDimension becomes a VTL (time) identifier;
++* Each possible Code Cj of the SDMX MeasureDimension is mapped to a VTL Measure, having the same name as the SDMX Code (i.e. Cj); the VTL Measure Cj is a new VTL component even if the SDMX data structure has not such a Component;
++* The SDMX MeasureDimension is not mapped to VTL (it disappears in the VTL Data Structure);
++* The SDMX Measure is not mapped to VTL as well (it disappears in the VTL Data Structure);
++* An SDMX DataAttribute is mapped in different ways according to its AttributeRelationship:
++** If, according to the SDMX AttributeRelationship, the values of the DataAttribute do not depend on the values of the MeasureDimension, the SDMX DataAttribute becomes a VTL Attribute having the same name. This happens if the AttributeRelationship is not specified (i.e. the DataAttribute does not depend on any DimensionComponent and therefore is at data set level), or if it refers to a set (or a group) of dimensions which does not include the MeasureDimension;
++** Otherwise, if, according to the SDMX AttributeRelationship, the values of the DataAttribute depend on the MeasureDimension, the SDMX DataAttribute is mapped to one VTL Attribute for each possible Code of the SDMX MeasureDimension. By default, the names of the VTL Attributes are obtained by concatenating the name of the SDMX DataAttribute and the names of the correspondent Code of the MeasureDimension separated by underscore. For example, if the SDMX DataAttribute is named DA and the possible Codes of the SDMX MeasureDimension are named C1, C2, …, Cn, then the corresponding VTL Attributes will be named DA_C1, DA_C2, …, DA_Cn (if different names are desired, they can be achieved afterwards by renaming the Attributes through VTL operators).
++** Like in the Basic mapping, the resulting VTL Attributes are considered as dependent on all the VTL identifiers (i.e. "at data point / observation level"), because VTL does not have the SDMX notion of Attribute Relationship.
--The summary mapping table of the "pivot" mapping from [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] for the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] data structures that contain a MeasureDimension is the following:
++The summary mapping table of the "pivot" mapping from SDMX to VTL for the SDMX data structures that contain a MeasureDimension is the following:
  (% style="width:769.294px" %)
--|(% style="width:401px" %)**[[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]]**|(% style="width:366px" %)**[[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]]**
--|(% style="width:401px" %)[[Dimension>>doc:xwiki:Glossary.Dimension.WebHome]]|(% style="width:366px" %)(Simple) Identifier
++|(% style="width:401px" %)**SDMX**|(% style="width:366px" %)**VTL**
++|(% style="width:401px" %)Dimension|(% style="width:366px" %)(Simple) Identifier
  |(% style="width:401px" %)TimeDimension|(% style="width:366px" %)(Time) Identifier
--|(% style="width:401px" %)MeasureDimension & one [[Measure>>doc:xwiki:Glossary.Measure.WebHome]]|(% style="width:366px" %)(((
--One [[Measure>>doc:xwiki:Glossary.Measure.WebHome]] for each [[Code>>doc:xwiki:Glossary.Code.WebHome]] of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] MeasureDimension
++|(% style="width:401px" %)MeasureDimension & one Measure|(% style="width:366px" %)(((
++One Measure for each Code of the SDMX MeasureDimension
  )))
--|(% style="width:401px" %)DataAttribute not depending on the MeasureDimension|(% style="width:366px" %)[[Attribute>>doc:xwiki:Glossary.Attribute.WebHome]]
++|(% style="width:401px" %)DataAttribute not depending on the MeasureDimension|(% style="width:366px" %)Attribute
  |(% style="width:401px" %)DataAttribute depending on the MeasureDimension|(% style="width:366px" %)(((
--One [[Attribute>>doc:xwiki:Glossary.Attribute.WebHome]] for each [[Code>>doc:xwiki:Glossary.Code.WebHome]] of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] MeasureDimension
++One Attribute for each Code of the SDMX MeasureDimension
  )))
--Using this mapping method, the [[components>>doc:xwiki:Glossary.Component.WebHome]] of the data structure can change in the conversion from [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] and it must be taken into account that the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] statements can reference only the [[components>>doc:xwiki:Glossary.Component.WebHome]] of the resulting [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] data structure.
++Using this mapping method, the components of the data structure can change in the conversion from SDMX to VTL and it must be taken into account that the VTL statements can reference only the components of the resulting VTL data structure.
--At observation / data point (% style="color:#2ecc71" %)level(%%), calling Cj (j=1, … n) the j^^th^^ [[Code>>doc:xwiki:Glossary.Code.WebHome]] of the MeasureDimension:
++At observation / data point level, calling Cj (j=1, … n) the j^^th^^ Code of the MeasureDimension:
--* The set of [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] observations having the same values for all the [[Dimensions>>doc:xwiki:Glossary.Dimension.WebHome]] except than the MeasureDimension become one multi-[[measure>>doc:xwiki:Glossary.Measure.WebHome]] [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] Data Point, having one [[Measure>>doc:xwiki:Glossary.Measure.WebHome]] for each [[Code>>doc:xwiki:Glossary.Code.WebHome]] Cj of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] MeasureDimension;
--* The values of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] simple [[Dimensions>>doc:xwiki:Glossary.Dimension.WebHome]], TimeDimension and DataAttributes not depending on the MeasureDimension (these [[components>>doc:xwiki:Glossary.Component.WebHome]] by definition have always the same values for all the observations of the set above) become the values of the corresponding [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] (simple) Identifiers, (time) Identifier and [[Attributes>>doc:xwiki:Glossary.Attribute.WebHome]].
--* The value of the [[Measure>>doc:xwiki:Glossary.Measure.WebHome]] of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] observation belonging to the set above and having MeasureDimension=Cj becomes the value of the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Measure>>doc:xwiki:Glossary.Measure.WebHome]] Cj
--* For the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] DataAttributes depending on the MeasureDimension, the value of the DataAttribute DA of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] observation belonging to the set above and having MeasureDimension=Cj becomes the value of the [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Attribute>>doc:xwiki:Glossary.Attribute.WebHome]] DA_Cj
++* The set of SDMX observations having the same values for all the Dimensions except than the MeasureDimension become one multi-measure VTL Data Point, having one Measure for each Code Cj of the SDMX MeasureDimension;
++* The values of the SDMX simple Dimensions, TimeDimension and DataAttributes not depending on the MeasureDimension (these components by definition have always the same values for all the observations of the set above) become the values of the corresponding VTL (simple) Identifiers, (time) Identifier and Attributes.
++* The value of the Measure of the SDMX observation belonging to the set above and having MeasureDimension=Cj becomes the value of the VTL Measure Cj
++* For the SDMX DataAttributes depending on the MeasureDimension, the value of the DataAttribute DA of the SDMX observation belonging to the set above and having MeasureDimension=Cj becomes the value of the VTL Attribute DA_Cj
  ==== 12.3.3.3 From SDMX DataAttributes to VTL Measures ====
--* In some cases, it may happen that the DataAttributes of the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] DataStructure need to be managed as [[Measures>>doc:xwiki:Glossary.Measure.WebHome]] in [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]]. Therefore, a variant of both the methods above consists in transforming all the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] DataAttributes in [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Measures>>doc:xwiki:Glossary.Measure.WebHome]]. When DataAttributes are converted to [[Measures>>doc:xwiki:Glossary.Measure.WebHome]], the two methods above are called Basic_A2M and Pivot_A2M (the suffix "A2M" stands for [[Attributes>>doc:xwiki:Glossary.Attribute.WebHome]] to [[Measures>>doc:xwiki:Glossary.Measure.WebHome]]). Obviously, the resulting [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] data structure is, in general, multi-[[measure>>doc:xwiki:Glossary.Measure.WebHome]] and does not contain [[Attributes>>doc:xwiki:Glossary.Attribute.WebHome]].
++* In some cases, it may happen that the DataAttributes of the SDMX DataStructure need to be managed as Measures in VTL. Therefore, a variant of both the methods above consists in transforming all the SDMX DataAttributes in VTL Measures. When DataAttributes are converted to Measures, the two methods above are called Basic_A2M and Pivot_A2M (the suffix "A2M" stands for Attributes to Measures). Obviously, the resulting VTL data structure is, in general, multi-measure and does not contain
--The Basic_A2M and Pivot_A2M behaves respectively like the Basic and Pivot methods, except that the final [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[components>>doc:xwiki:Glossary.Component.WebHome]], which according to the Basic and Pivot methods would have had the role of [[Attribute>>doc:xwiki:Glossary.Attribute.WebHome]], assume instead the role of [[Measure>>doc:xwiki:Glossary.Measure.WebHome]].
++Attributes.
--Proper [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] features allow changing the role of specific [[attributes>>doc:xwiki:Glossary.Attribute.WebHome]] even after the [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] mapping: they can be useful when only some of the DataAttributes need to be managed as [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] [[Measures>>doc:xwiki:Glossary.Measure.WebHome]].
++The Basic_A2M and Pivot_A2M behaves respectively like the Basic and Pivot methods, except that the final VTL components, which according to the Basic and Pivot methods would have had the role of Attribute, assume instead the role of Measure.
++Proper VTL features allow changing the role of specific attributes even after the SDMX to VTL mapping: they can be useful when only some of the DataAttributes need to be managed as VTL Measures.
++
  === 12.3.4 Mapping from VTL to SDMX data structures ===
  ==== 12.3.4.1 Basic Mapping ====
--The main mapping method **from [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]] to [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]]** is called **Basic **mapping as well.
++The main mapping method **from VTL to SDMX** is called **Basic **mapping as well.
  This is considered as the default mapping method and is applied unless a different method is specified through the VtlMappingScheme and VtlDataflowMapping classes.
--The method consists in leaving the [[components>>doc:xwiki:Glossary.Component.WebHome]] unchanged and maintaining their names and roles in [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]], according to the following mapping table, which is the same as the basic mapping from [[SDMX>>doc:xwiki:Glossary.Statistical data and metadata exchange.WebHome]] to [[VTL>>doc:xwiki:Glossary.Validation and transformation language.WebHome]], only seen in the opposite direction.
++The method consists in leaving the components unchanged and maintaining their names and roles in SDMX, according to the following mapping table, which is the same as the basic mapping from SDMX to VTL, only seen in the opposite direction.
  Mapping table:
@@ -412,8 +412,13 @@
  It should be noted that the desired VTL Data Sets (i.e. of the kind ‘DF1(1.0.0)/// INDICATORvalue//.//COUNTRYvalue//’) can be obtained also by applying the VTL operator “**sub**” (subspace) to the Dataflow DF1(1.0.0), like in the following VTL expression:
--[[image:1747388275998-621.png]]
++‘DF1(1.0.0)/POPULATION.USA’ :=
++DF1(1.0.0) [ sub INDICATOR=“POPULATION”, COUNTRY=“USA” ];
++‘DF1(1.0.0)/POPULATION.CANADA’ :=
++DF1(1.0.0) [ sub INDICATOR=“POPULATION”, COUNTRY=“CANADA” ];
++… … …
++
  In fact the VTL operator “sub” has exactly the same behaviour. Therefore, mapping different parts of a SDMX Dataflow to different VTL Data Sets in the direction from SDMX to VTL through the ordered concatenation notation is equivalent to a proper use of the operator “**sub**” on such a Dataflow.{{footnote}}In case the ordered concatenation notation is used, the VTL Transformation described above, e.g. ‘DF1(1.0)/POPULATION.USA’ := DF1(1.0) [ sub INDICATOR=“POPULATION”, COUNTRY=“USA”], is implicitly executed. In order to test the overall compliance of the VTL program to the VTL consistency rules, it has to be considered as part of the VTL program even if it is not explicitly coded.{{/footnote}}
  In the direction from SDMX to VTL it is allowed to omit the value of one or more
@@ -424,7 +424,8 @@
  This is equivalent to the application of the VTL “sub” operator only to the identifier //INDICATOR//:
--[[image:1747388244829-693.png]]
++‘DF1(1.0.0)/POPULATION.’ :=
++DF1(1.0.0) [ sub INDICATOR=“POPULATION” ];
  Therefore the VTL Data Set ‘DF1(1.0.0)/POPULATION.’ would have the identifiers COUNTRY and TIME_PERIOD.
@@ -451,17 +451,36 @@
  Some examples follow, for some specific values of INDICATOR and COUNTRY:
--[[image:1747388222879-916.png]]
++‘DF2(1.0.0)/GDPPERCAPITA.USA’ <- expression11; ‘DF2(1.0.0)/GDPPERCAPITA.CANADA’ <- expression12;
--[[image:1747388206717-256.png]]
++… … …
++‘DF2(1.0.0)/POPGROWTH.USA’ <- expression21;
++‘DF2(1.0.0)/POPGROWTH.CANADA’ <- expression22;
++… … …
  As said, it is assumed that these VTL derived Data Sets have the TIME_PERIOD as the only identifier. In the mapping from VTL to SMDX, the Dimensions INDICATOR and COUNTRY are added to the VTL data structure on order to obtain the SDMX one, with the following values respectively:
--[[image:1747388148322-387.png]]
++VTL dataset INDICATOR value COUNTRY value
++‘DF2(1.0.0)/GDPPERCAPITA.USA’ GDPPERCAPITA USA
++‘DF2(1.0.0)/GDPPERCAPITA.CANADA’ GDPPERCAPITA CANADA … … …
++‘DF2(1.0.0)/POPGROWTH.USA’ POPGROWTH USA
++‘DF2(1.0.0)/POPGROWTH.CANADA’ POPGROWTH CANADA
++… … …
++
  It should be noted that the application of this many-to-one mapping from VTL to SDMX is equivalent to an appropriate sequence of VTL Transformations. These use the VTL operator “calc” to add the proper VTL identifiers (in the example, INDICATOR and COUNTRY) and to assign to them the proper values and the operator “union” in order to obtain the final VTL dataset (in the example DF2(1.0.0)), that can be mapped oneto-one to the homonymous SDMX Dataflow. Following the same example, these VTL Transformations would be:
--[[image:1747388179021-814.png]]
++DF2bis_GDPPERCAPITA_USA := ‘DF2(1.0.0)/GDPPERCAPITA.USA’ [calc identifier INDICATOR := ”GDPPERCAPITA”, identifier COUNTRY := ”USA”];
++DF2bis_GDPPERCAPITA_CANADA := ‘DF2(1.0.0)/GDPPERCAPITA.CANADA’ [calc identifier INDICATOR:=”GDPPERCAPITA”, identifier COUNTRY:=”CANADA”]; … … …
++DF2bis_POPGROWTH_USA := ‘DF2(1.0.0)/POPGROWTH.USA’
++[calc identifier INDICATOR := ”POPGROWTH”, identifier COUNTRY := ”USA”];
++DF2bis_POPGROWTH_CANADA’ := ‘DF2(1.0.0)/POPGROWTH.CANADA’ [calc identifier INDICATOR := ”POPGROWTH”, identifier COUNTRY := ”CANADA”]; … … …
++DF2(1.0) <- UNION (DF2bis_GDPPERCAPITA_USA’,
++DF2bis_GDPPERCAPITA_CANADA’,
++… ,
++DF2bis_POPGROWTH_USA’,
++DF2bis_POPGROWTH_CANADA’
++…);
  In other words, starting from the datasets explicitly calculated through VTL (in the example ‘DF2(1.0)/GDPPERCAPITA.USA’ and so on), the first step consists in calculating other (non-persistent) VTL datasets (in the example
@@ -475,30 +475,38 @@
  With reference to the VTL “model for Variables and Value domains”, the following additional mappings have to be considered:
--(% style="width:895.294px" %)
--|(% style="width:278px" %)**VTL**|(% style="width:613px" %)**SDMX**
--|(% style="width:278px" %)**Data Set Component**|(% style="width:613px" %)Although this abstraction exists in SDMX, it does not have an explicit definition and correspond to a Component (either a DimensionComponent or a Measure or a DataAttribute) belonging to one specific Dataflow{{footnote}}Through SDMX Constraints, it is possible to specify the values that a Component of a Dataflow can assume.{{/footnote}}
--|(% style="width:278px" %)**Represented Variable**|(% style="width:613px" %)(((
++(% style="width:1170.29px" %)
++|**VTL**|(% style="width:754px" %)**SDMX**
++|**Data Set Component**|(% style="width:754px" %)Although this abstraction exists in SDMX, it does not have an explicit definition and correspond to a Component (either a DimensionComponent or a Measure or a DataAttribute) belonging to one specific Dataflow{{footnote}}Through SDMX Constraints, it is possible to specify the values that a Component of a Dataflow can assume.{{/footnote}}
++|**Represented Variable**|(% style="width:754px" %)(((
  **Concept** with a definite
  Representation
  )))
--|(% style="width:278px" %)**Value Domain**|(% style="width:613px" %)(((
--**Representation** (see the Structure Pattern in the Base Package)
++|**Value Domain**|(% style="width:754px" %)(((
++**Representation** (see the Structure
++
++Pattern in the Base Package)
  )))
--|(% style="width:278px" %)**Enumerated Value Domain /
--Code List**|(% style="width:613px" %)**Codelist**
--|(% style="width:278px" %)**Code**|(% style="width:613px" %)(((
--**Code** (for enumerated DimensionComponent, Measure, DataAttribute)
++|**Enumerated Value Domain / Code List**|(% style="width:754px" %)**Codelist**
++|**Code**|(% style="width:754px" %)(((
++**Code** (for enumerated
++
++DimensionComponent, Measure, DataAttribute)
  )))
--|(% style="width:278px" %)**Described Value Domain**|(% style="width:613px" %)(((
--non-enumerated** Representation **(having Facets / ExtendedFacets, see the Structure Pattern in the Base Package)
++|**Described Value Domain**|(% style="width:754px" %)(((
++non-enumerated** Representation**
++
++(having Facets / ExtendedFacets, see the Structure Pattern in the Base Package)
  )))
--|(% style="width:278px" %)**Value**|(% style="width:613px" %)Although this abstraction exists in SDMX, it does not have an explicit definition and correspond to a **Code** of a Codelist (for enumerated Representations) or to a valid **value **(for non-enumerated** **Representations)
--|(% style="width:278px" %)**Value Domain Subset / Set**|(% style="width:613px" %)This abstraction does not exist in SDMX
--|(% style="width:278px" %)**Enumerated Value Domain Subset / Enumerated Set**|(% style="width:613px" %)This abstraction does not exist in SDMX
--|(% style="width:278px" %)**Described Value Domain Subset / Described Set**|(% style="width:613px" %)This abstraction does not exist in SDMX
--|(% style="width:278px" %)**Set list**|(% style="width:613px" %)This abstraction does not exist in SDMX
++|**Value**|(% style="width:754px" %)Although this abstraction exists in SDMX, it does not have an explicit definition and correspond to a **Code** of a Codelist (for enumerated Representations) or
++| |(% style="width:754px" %)(((
++to a valid **value **(for non-enumerated** **Representations)
++)))
++|**Value Domain Subset / Set**|(% style="width:754px" %)This abstraction does not exist in SDMX
++|**Enumerated Value Domain Subset / Enumerated Set**|(% style="width:754px" %)This abstraction does not exist in SDMX
++|**Described Value Domain Subset / Described Set**|(% style="width:754px" %)This abstraction does not exist in SDMX
++|**Set list**|(% style="width:754px" %)This abstraction does not exist in SDMX
  The main difference between VTL and SDMX relies on the fact that the VTL artefacts for defining subsets of Value Domains do not exist in SDMX, therefore the VTL features for referring to predefined subsets are not available in SDMX. These artefacts are the Value Domain Subset (or Set), either enumerated or described, the Set List (list of values belonging to enumerated subsets) and the Data Set Component (aimed at defining the set of values that the Component of a Data Set can take, possibly a subset of the codes of Value Domain).
@@ -524,7 +524,7 @@
  The VTL data types are sub-divided in scalar types (like integers, strings, etc.), which are the types of the scalar values, and compound types (like Data Sets, Components, Rulesets, etc.), which are the types of the compound structures. See below the diagram of the VTL data types, taken from the VTL User Manual:
--[[image:1747388434672-948.png]]
++[[image:SDMX 3-0-0 SECTION 6 FINAL-1.0_en_e3df33ae.png||height="543" width="483"]]
  (% class="wikigeneratedid" id="HFigure222013VTLDataTypes" %)
  **Figure 22 – VTL Data Types**
@@ -533,10 +533,13 @@
  The VTL basic scalar types are listed below and follow a hierarchical structure in terms of supersets/subsets (e.g. "scalar" is the superset of all the basic scalar types):
--[[image:1747388465321-274.png]]
  **Figure 23 – VTL Basic Scalar Types**
++(((
++
++)))
++
  === 12.4.2 VTL basic scalar types and SDMX data types ===
  The VTL assumes that a basic scalar type has a unique internal representation and can have more external representations.
@@ -750,53 +750,53 @@
  The custom output formats can be specified by means of the VTL formatting mask described in the section "Type Conversion and Formatting Mask" of the VTL Reference Manual. Such a section describes the masks for the VTL basic scalar types "number", "integer", "date", "time", "time_period" and "duration" and gives examples. As for the types "string" and "boolean" the VTL conventions are extended with some other special characters as described in the following table.
--(% style="width:713.294px" %)
--|(% colspan="2" style="width:710px" %)VTL special characters for the formatting masks
--|(% colspan="2" style="width:710px" %)
--|(% colspan="2" style="width:710px" %)Number
--|D|(% style="width:486px" %)one numeric digit (if the scientific notation is adopted, D is only for the mantissa)
--|E|(% style="width:486px" %)one numeric digit (for the exponent of the scientific notation)
--|. (dot)|(% style="width:486px" %)possible separator between the integer and the decimal parts.
--|, (comma)|(% style="width:486px" %)possible separator between the integer and the decimal parts.
--| |(% style="width:486px" %)
--|(% colspan="2" style="width:710px" %)Time and duration
--|C|(% style="width:486px" %)century
--|Y|(% style="width:486px" %)year
--|S|(% style="width:486px" %)semester
--|Q|(% style="width:486px" %)quarter
--|M|(% style="width:486px" %)month
--|W|(% style="width:486px" %)week
--|D|(% style="width:486px" %)day
--|h|(% style="width:486px" %)hour digit (by default on 24 hours)
--|M|(% style="width:486px" %)minute
--|S|(% style="width:486px" %)second
--|D|(% style="width:486px" %)decimal of second
--|P|(% style="width:486px" %)period indicator (representation in one digit for the duration)
--|P|(% style="width:486px" %)number of the periods specified in the period indicator
--|AM/PM|(% style="width:486px" %)indicator of AM / PM (e.g. am/pm for "am" or "pm")
--|MONTH|(% style="width:486px" %)uppercase textual representation of the month (e.g., JANUARY for January)
--|DAY|(% style="width:486px" %)uppercase textual representation of the day (e.g., MONDAY for Monday)
--|Month|(% style="width:486px" %)lowercase textual representation of the month (e.g., january)
--|Day|(% style="width:486px" %)lowercase textual representation of the month (e.g., monday)
--|Month|(% style="width:486px" %)First character uppercase, then lowercase textual representation of the month (e.g., January)
--|Day|(% style="width:486px" %)First character uppercase, then lowercase textual representation of the day using (e.g. Monday)
--| |(% style="width:486px" %)
--|(% colspan="2" style="width:710px" %)String
--|X|(% style="width:486px" %)any string character
--|Z|(% style="width:486px" %)any string character from "A" to "z"
--|9|(% style="width:486px" %)any string character from "0" to "9"
--| |(% style="width:486px" %)
--|(% colspan="2" style="width:710px" %)Boolean
--|B|(% style="width:486px" %)Boolean using "true" for True and "false" for False
--|1|(% style="width:486px" %)Boolean using "1" for True and "0" for False
--|0|(% style="width:486px" %)Boolean using "0" for True and "1" for False
--| |(% style="width:486px" %)
--|(% colspan="2" style="width:710px" %)Other qualifiers
--|*|(% style="width:486px" %)an arbitrary number of digits (of the preceding type)
--|+|(% style="width:486px" %)at least one digit (of the preceding type)
--|( )|(% style="width:486px" %)optional digits (specified within the brackets)
--|\|(% style="width:486px" %)prefix for the special characters that must appear in the mask
--|N|(% style="width:486px" %)fixed number of digits used in the preceding textual representation of the month or the day
++|(% colspan="2" %)VTL special characters for the formatting masks
++|(% colspan="2" %)
++|(% colspan="2" %)Number
++|D|one numeric digit (if the scientific notation is adopted, D is only for the mantissa)
++|E|one numeric digit (for the exponent of the scientific notation)
++|. (dot)|possible separator between the integer and the decimal parts.
++|, (comma)|possible separator between the integer and the decimal parts.
++| |
++|(% colspan="2" %)Time and duration
++|C|century
++|Y|year
++|S|semester
++|Q|quarter
++|M|month
++|W|week
++|D|day
++|h|hour digit (by default on 24 hours)
++|M|minute
++|S|second
++|D|decimal of second
++|P|period indicator (representation in one digit for the duration)
++|P|number of the periods specified in the period indicator
++|AM/PM|indicator of AM / PM (e.g. am/pm for "am" or "pm")
++|MONTH|uppercase textual representation of the month (e.g., JANUARY for January)
++|DAY|uppercase textual representation of the day (e.g., MONDAY for Monday)
++|Month|lowercase textual representation of the month (e.g., january)
++|Day|lowercase textual representation of the month (e.g., monday)
++|Month|First character uppercase, then lowercase textual representation of the month (e.g., January)
++|Day|First character uppercase, then lowercase textual representation of the day using (e.g. Monday)
++| |
++|(% colspan="2" %)String
++|X|any string character
++|Z|any string character from "A" to "z"
++|9|any string character from "0" to "9"
++| |
++|(% colspan="2" %)Boolean
++|B|Boolean using "true" for True and "false" for False
++|1|Boolean using "1" for True and "0" for False
++|0|Boolean using "0" for True and "1" for False
++| |
++|(% colspan="2" %)Other qualifiers
++|*|an arbitrary number of digits (of the preceding type)
++|+|at least one digit (of the preceding type)
++|( )|optional digits (specified within the brackets)
++|\|prefix for the special characters that must appear in the mask
++|N|fixed number of digits used in the preceding textual representation of the month or the day
++| |
  The default conversion, either standard or customized, can be used to deduce automatically the representation of the components of the result of a VTL Transformation. In alternative, the representation of the resulting SDMX Dataflow can be given explicitly by providing its DataStructureDefinition. In other words, the representation specified in the DSD, if available, overrides any default conversion{{footnote}}The representation given in the DSD should obviously be compatible with the VTL data type.{{/footnote}}.

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