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1 -{{box title="**Contents**"}}
2 -{{toc/}}
3 -{{/box}}
1 += 12 Validation and Transformation Language (VTL) =
4 4  
5 5  == 12.1 Introduction ==
6 6  
7 -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:
5 +The Validation and Transformation Language (VTL) supports the definition of Transformations, which are algorithms to calculate new data starting from already existing ones^^[[^^5^^>>path:#sdfootnote5sym||name="sdfootnote5anc"]]^^. The purpose of the VTL in the SDMX context is to enable the:
8 8  
9 9  * definition of validation and transformation algorithms, in order to specify how to calculate new data from existing ones;
10 10  * 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);
... ... @@ -12,7 +12,7 @@
12 12  
13 13  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").
14 14  
15 -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).
13 +The VTL language can be applied to SDMX artefacts by mapping the SDMX IM model artefacts to the model artefacts that VTL can manipulate^^[[^^6^^>>path:#sdfootnote6sym||name="sdfootnote6anc"]]^^. 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).
16 16  
17 17  The VTL programs (Transformation Schemes) are represented in SDMX through the TransformationScheme maintainable class which is composed of
18 18  
... ... @@ -30,7 +30,7 @@
30 30  
31 31  In any case, the aliases used in the VTL Transformations have to be mapped to the
32 32  
33 -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.
31 +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^^[[^^7^^>>path:#sdfootnote7sym||name="sdfootnote7anc"]]^^ or User Defined Operators^^[[^^8^^>>path:#sdfootnote8sym||name="sdfootnote8anc"]]^^ to reference SDMX artefacts. A VtlMappingScheme is a container for zero or more VtlMapping.
34 34  
35 35  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.
36 36  
... ... @@ -40,7 +40,7 @@
40 40  
41 41  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.
42 42  
43 -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:
41 +The SDMX URN^^[[^^9^^>>path:#sdfootnote9sym||name="sdfootnote9anc"]]^^ is the concatenation of the following parts, separated by special symbols like dot, equal, asterisk, comma, and parenthesis:
44 44  
45 45  * SDMXprefix
46 46  * SDMX-IM-package-name
... ... @@ -48,13 +48,15 @@
48 48  * agency-id
49 49  * maintainedobject-id
50 50  * maintainedobject-version
51 -* container-object-id{{footnote}}The container-object-id can repeat and may not be present.{{/footnote}}
49 +* container-object-id ^^[[^^10^^>>path:#sdfootnote10sym||name="sdfootnote10anc"]]^^
52 52  * object-id
53 53  
54 54  The generic structure of the URN is the following:
55 55  
56 -SDMXprefix.SDMX-IM-package-name.class-name=agency-id:maintainedobject-id (maintainedobject-version).*container-object-id.object-id
54 +SDMXprefix.SDMX-IM-package-name.class-name=agency-id:maintainedobject-id
57 57  
56 +(maintainedobject-version).*container-object-id.object-id
57 +
58 58  The **SDMXprefix** is "urn:sdmx:org", always the same for all SDMX artefacts.
59 59  
60 60  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".
... ... @@ -63,10 +63,13 @@
63 63  
64 64  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).
65 65  
66 -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:
66 +The maintainedobject-id is the name of the maintained object which the artefact belongs to, and in case the artefact itself is maintainable^^[[^^11^^>>path:#sdfootnote11sym||name="sdfootnote11anc"]]^^, coincides with the name of the artefact. Therefore the maintainedobject-id depends on the class of the artefact:
67 67  
68 68  * if the artefact is a Dataflow, which is a maintainable class, the maintainedobject-id is the Dataflow name (dataflow-id);
69 -* 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;
69 +* if the artefact is a Dimension, Measure, TimeDimension or DataAttribute, which are not maintainable and belong to the
70 +
71 +DataStructure maintainable class, the maintainedobject-id is the name of the DataStructure (dataStructure-id) which the artefact belongs to;
72 +
70 70  * 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;
71 71  * if the artefact is a Codelist, which is a maintainable class, the maintainedobject-id is the Codelist name (codelist-id).
72 72  
... ... @@ -79,10 +79,12 @@
79 79  * 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)
80 80  * if the artefact is a Concept (the object-id is the name of the Concept)
81 81  
82 -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}}:
85 +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^^[[^^12^^>>path:#sdfootnote12sym||name="sdfootnote12anc"]]^^:
83 83  
84 84  'urn:sdmx:org.sdmx.infomodel.datastructure.Dataflow=AG:DFR(1.0.0)' <-
88 +
85 85  'urn:sdmx:org.sdmx.infomodel.datastructure.Dataflow=AG:DF1(1.0.0)' +
90 +
86 86  'urn:sdmx:org.sdmx.infomodel.datastructure.Dataflow=AG:DF2(1.0.0)'
87 87  
88 88  === 12.2.3 Abbreviation of the URN ===
... ... @@ -91,10 +91,10 @@
91 91  
92 92  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.
93 93  
94 -* 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:
99 +* 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** &nbsp;**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:
95 95  ** "datastructure" for the classes Dataflow, Dimension, TimeDimension, Measure, DataAttribute, o "conceptscheme" for the class Concept, o "codelist" for the class Codelist.
96 -* 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}}.
97 -* 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).
101 +* 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^^[[^^13^^>>path:#sdfootnote13sym||name="sdfootnote13anc"]]^^, the SDMX class can be deduced from the mapping rules between VTL and SDMX (see the section "Mapping between VTL and SDMX" hereinafter)^^[[^^14^^>>path:#sdfootnote14sym||name="sdfootnote14anc"]]^^.
102 +* 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^^[[^^15^^>>path:#sdfootnote15sym||name="sdfootnote15anc"]]^^. 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).
98 98  * 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;
99 99  ** 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;
100 100  ** 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;
... ... @@ -107,7 +107,9 @@
107 107  For example, the full formulation that uses the complete URN shown at the end of the previous paragraph:
108 108  
109 109  'urn:sdmx:org.sdmx.infomodel.datastructure.Dataflow=AG:DFR(1.0.0)' :=
115 +
110 110  'urn:sdmx:org.sdmx.infomodel.datastructure.Dataflow=AG:DF1(1.0.0)' +
117 +
111 111  'urn:sdmx:org.sdmx.infomodel.datastructure.Dataflow=AG:DF2(1.0.0)'
112 112  
113 113  by omitting all the non-essential parts would become simply:
... ... @@ -114,11 +114,11 @@
114 114  
115 115  DFR := DF1 + DF2
116 116  
117 -The references to the Codelists can be simplified similarly. For example, given the non-abbreviated reference to the Codelist AG:CL_FREQ(1.0.0), which is{{footnote}}Single quotes are needed because this reference is not a VTL regular name.{{/footnote}}:
124 +The references to the Codelists can be simplified similarly. For example, given the non-abbreviated reference to the Codelist AG:CL_FREQ(1.0.0), which is^^[[^^16^^>>path:#sdfootnote16sym||name="sdfootnote16anc"]]^^:
118 118  
119 119  'urn:sdmx:org.sdmx.infomodel.codelist.Codelist=AG:CL_FREQ(1.0.0)'
120 120  
121 -if the Codelist is referenced from a RulesetScheme belonging to the agency AG, omitting all the optional parts, the abbreviated reference would become simply{{footnote}}Single quotes are not needed in this case because CL_FREQ is a VTL regular name.{{/footnote}}:
128 +if the Codelist is referenced from a RulesetScheme belonging to the agency AG, omitting all the optional parts, the abbreviated reference would become simply^^19^^:
122 122  
123 123  CL_FREQ
124 124  
... ... @@ -132,7 +132,7 @@
132 132  
133 133  SECTOR
134 134  
135 -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}}:
142 +For example, the Transformation for renaming the component SECTOR of the Dataflow DF1 into SEC can be written as^^[[^^17^^>>path:#sdfootnote17sym||name="sdfootnote17anc"]]^^:
136 136  
137 137  'DFR(1.0.0)' := 'DF1(1.0.0)' [rename SECTOR to SEC]
138 138  
... ... @@ -164,9 +164,9 @@
164 164  
165 165  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.
166 166  
167 -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}}.
174 +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^^[[^^18^^>>path:#sdfootnote18sym||name="sdfootnote18anc"]]^^.
168 168  
169 -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}}
176 +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.^^[[^^19^^>>path:#sdfootnote19sym||name="sdfootnote19anc"]]^^
170 170  
171 171  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.
172 172  
... ... @@ -178,15 +178,15 @@
178 178  
179 179  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.
180 180  
181 -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}}.
188 +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^^[[^^20^^>>path:#sdfootnote20sym||name="sdfootnote20anc"]]^^.
182 182  
183 183  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).
184 184  
185 185  === 12.3.2 General mapping of VTL and SDMX data structures ===
186 186  
187 -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}}.
194 +This section makes reference to the VTL "Model for data and their structure"^^[[^^21^^>>path:#sdfootnote21sym||name="sdfootnote21anc"]]^^ and the correspondent SDMX "Data Structure Definition"^^[[^^22^^>>path:#sdfootnote22sym||name="sdfootnote22anc"]]^^.
188 188  
189 -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}}
196 +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).^^[[^^23^^>>path:#sdfootnote23sym||name="sdfootnote23anc"]]^^
190 190  
191 191  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.
192 192  
... ... @@ -206,28 +206,32 @@
206 206  
207 207  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:
208 208  
209 -(% style="width:529.294px" %)
210 -|(% style="width:151px" %)**SDMX**|(% style="width:375px" %)**VTL**
211 -|(% style="width:151px" %)Dimension|(% style="width:375px" %)(Simple) Identifier
212 -|(% style="width:151px" %)TimeDimension|(% style="width:375px" %)(Time) Identifier
213 -|(% style="width:151px" %)Measure|(% style="width:375px" %)Measure
214 -|(% style="width:151px" %)DataAttribute|(% style="width:375px" %)Attribute
216 +|**SDMX**|**VTL**
217 +|Dimension|(Simple) Identifier
218 +|TimeDimension|(Time) Identifier
215 215  
220 +[[image:SDMX 3-0-0 SECTION 6 FINAL-1.0_en_59eee18f.gif||alt="Shape4" height="1" width="192"]]
221 +
222 +|Measure|Measure
223 +|DataAttribute|Attribute
224 +
216 216  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).
217 217  
218 -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.
227 +With the Basic mapping, one SDMX observation^^27^^ generates one VTL data point.
219 219  
220 -==== 12.3.3.2 Pivot Mapping ====
229 +**12.3.3.2 Pivot Mapping**
221 221  
222 222  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.
223 223  
224 -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}}.
233 +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
225 225  
235 +MeasureDimensions considered as a joint variable^^[[^^24^^>>path:#sdfootnote24sym||name="sdfootnote24anc"]]^^.
236 +
226 226  Among other things, the Pivot method provides also backward compatibility with the SDMX 2.1 data structures that contained a MeasureDimension.
227 227  
228 228  If applied to SDMX structures that do not contain any MeasureDimension, this method behaves like the Basic mapping (see the previous paragraph).
229 229  
230 -Here an SDMX observation is meant to correspond to one combination of values of the DimensionComponents.
241 +^^27^^ Here an SDMX observation is meant to correspond to one combination of values of the DimensionComponents.
231 231  
232 232  The SDMX structures that contain a MeasureDimension are mapped as described below (this mapping is equivalent to a pivoting operation):
233 233  
... ... @@ -385,20 +385,20 @@
385 385  
386 386  Until now it has been assumed to map one SMDX Dataflow to one VTL Data Set and vice-versa. This mapping one-to-one is not mandatory according to VTL because a VTL Data Set is meant to be a set of observations (data points) on a logical plane, having the same logical data structure and the same general meaning, independently of the possible physical representation or storage (see VTL 2.0 User Manual page 24), therefore a SDMX Dataflow can be seen either as a unique set of data observations (corresponding to one VTL Data Set) or as the union of many sets of data observations (each one corresponding to a distinct VTL Data Set).
387 387  
388 -As a matter of fact, in some cases it can be useful to define VTL operations involving definite parts of a SDMX Dataflow instead than the whole.^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^25^^>>path:#sdfootnote25sym||name="sdfootnote25anc"]](%%)^^
399 +As a matter of fact, in some cases it can be useful to define VTL operations involving definite parts of a SDMX Dataflow instead than the whole.^^[[^^25^^>>path:#sdfootnote25sym||name="sdfootnote25anc"]]^^
389 389  
390 -Therefore, in order to make the coding of VTL operations simpler when applied on parts of SDMX Dataflows, it is allowed to map distinct parts of a SDMX Dataflow to distinct VTL Data Sets according to the following rules and conventions. This kind of mapping is possible both from SDMX to VTL and from VTL to SDMX, as better explained below.^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^26^^>>path:#sdfootnote26sym||name="sdfootnote26anc"]](%%)^^
401 +Therefore, in order to make the coding of VTL operations simpler when applied on parts of SDMX Dataflows, it is allowed to map distinct parts of a SDMX Dataflow to distinct VTL Data Sets according to the following rules and conventions. This kind of mapping is possible both from SDMX to VTL and from VTL to SDMX, as better explained below.^^[[^^26^^>>path:#sdfootnote26sym||name="sdfootnote26anc"]]^^
391 391  
392 392  Given a SDMX Dataflow and some predefined Dimensions of its DataStructure, it is allowed to map the subsets of observations that have the same combination of values for such Dimensions to correspondent VTL datasets.
393 393  
394 394  For example, assuming that the SDMX Dataflow DF1(1.0.0) has the Dimensions INDICATOR, TIME_PERIOD and COUNTRY, and that the user declares the Dimensions INDICATOR and COUNTRY as basis for the mapping (i.e. the mapping dimensions): the observations that have the same values for INDICATOR and COUNTRY would be mapped to the same VTL dataset (and vice-versa). In practice, this kind mapping is obtained like follows:
395 395  
396 -* For a given SDMX Dataflow, the user (VTL definer) declares the DimensionComponents on which the mapping will be based, in a given order.^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^27^^>>path:#sdfootnote27sym||name="sdfootnote27anc"]](%%)^^ Following the example above, imagine that the user declares the Dimensions INDICATOR and COUNTRY.
407 +* For a given SDMX Dataflow, the user (VTL definer) declares the DimensionComponents on which the mapping will be based, in a given order.^^[[^^27^^>>path:#sdfootnote27sym||name="sdfootnote27anc"]]^^ Following the example above, imagine that the user declares the Dimensions INDICATOR and COUNTRY.
397 397  * The VTL Data Set is given a name using a special notation also called “ordered concatenation” and composed of the following parts:
398 398  ** The reference to the SDMX Dataflow (expressed according to the rules described in the previous paragraphs, i.e. URN, abbreviated URN or another alias); for example DF(1.0.0);
399 -** a slash (“/”) as a separator; ^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^28^^>>path:#sdfootnote28sym||name="sdfootnote28anc"]](%%)^^
410 +** a slash (“/”) as a separator; ^^[[^^28^^>>path:#sdfootnote28sym||name="sdfootnote28anc"]]^^
400 400  
401 -The reference to a specific part of the SDMX Dataflow above, expressed as the concatenation of the values that the SDMX DimensionComponents declared above must have, separated by dots (“.”) and written in the order in which these DimensionComponents are defined^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^29^^>>path:#sdfootnote29sym||name="sdfootnote29anc"]](%%)^^. For example POPULATION.USA would mean that such a VTL Data Set is mapped to the SDMX observations for which the dimension //INDICATOR// is equal to POPULATION and the dimension //COUNTRY// is equal to USA.
412 +The reference to a specific part of the SDMX Dataflow above, expressed as the concatenation of the values that the SDMX DimensionComponents declared above must have, separated by dots (“.”) and written in the order in which these DimensionComponents are defined^^[[^^29^^>>path:#sdfootnote29sym||name="sdfootnote29anc"]]^^. For example POPULATION.USA would mean that such a VTL Data Set is mapped to the SDMX observations for which the dimension //INDICATOR// is equal to POPULATION and the dimension //COUNTRY// is equal to USA.
402 402  
403 403  In the VTL Transformations, this kind of dataset name must be referenced between single quotes because the slash (“/”) is not a regular character according to the VTL rules.
404 404  
... ... @@ -414,15 +414,15 @@
414 414  
415 415  Let us now analyse the different meaning of this kind of mapping in the two mapping directions, i.e. from SDMX to VTL and from VTL to SDMX.
416 416  
417 -As already said, the mapping from SDMX to VTL happens when the SDMX dataflows are operand of VTL Transformations, instead the mapping from VTL to SDMX happens when the VTL Data Sets that is result of Transformations^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^30^^>>path:#sdfootnote30sym||name="sdfootnote30anc"]](%%)^^ need to be treated as SDMX objects. This kind of mapping can be applied independently in the two directions and the Dimensions on which the mapping is based can be different in the two directions: these Dimensions are defined in the ToVtlSpaceKey and in the FromVtlSpaceKey classes respectively.
428 +As already said, the mapping from SDMX to VTL happens when the SDMX dataflows are operand of VTL Transformations, instead the mapping from VTL to SDMX happens when the VTL Data Sets that is result of Transformations^^[[^^30^^>>path:#sdfootnote30sym||name="sdfootnote30anc"]]^^ need to be treated as SDMX objects. This kind of mapping can be applied independently in the two directions and the Dimensions on which the mapping is based can be different in the two directions: these Dimensions are defined in the ToVtlSpaceKey and in the FromVtlSpaceKey classes respectively.
418 418  
419 419  First, let us see what happens in the __mapping direction from SDMX to VTL__, i.e. when parts of a SDMX Dataflow (e.g. DF1(1.0.0)) need to be mapped to distinct VTL Data Sets that are operand of some VTL Transformations.
420 420  
421 421  As already said, each VTL Data Set is assumed to contain all the observations of the
422 422  
423 -SDMX Dataflow having INDICATOR=//INDICATORvalue //and COUNTRY=// COUNTRYvalue//. For example, the VTL dataset ‘DF1(1.0.0)/POPULATION.USA’ would contain all the observations of DF1(1.0.0) having INDICATOR = POPULATION and COUNTRY = USA.
434 +SDMX Dataflow having INDICATOR=//INDICATORvalue //and COUNTRY=// COUNTRYvalue//. For example, the VTL dataset ‘DF1(1.0.0)/POPULATION.USA’ would contain all the observations of DF1(1.0.0) having INDICATOR = POPULATION and COUNTRY = USA.
424 424  
425 -In order to obtain the data structure of these VTL Data Sets from the SDMX one, it is assumed that the SDMX DimensionComponents on which the mapping is based are dropped, i.e. not maintained in the VTL data structure; this is possible because their values are fixed for each one of the invoked VTL Data Sets^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^31^^>>path:#sdfootnote31sym||name="sdfootnote31anc"]](%%)^^. After that, the mapping method from SDMX to VTL specified for the Dataflow DF1(1.0.0) is applied (i.e.
436 +In order to obtain the data structure of these VTL Data Sets from the SDMX one, it is assumed that the SDMX DimensionComponents on which the mapping is based are dropped, i.e. not maintained in the VTL data structure; this is possible because their values are fixed for each one of the invoked VTL Data Sets^^[[^^31^^>>path:#sdfootnote31sym||name="sdfootnote31anc"]]^^. After that, the mapping method from SDMX to VTL specified for the Dataflow DF1(1.0.0) is applied (i.e.
426 426  
427 427  basic, pivot …).
428 428  
... ... @@ -442,7 +442,7 @@
442 442  
443 443  … … …
444 444  
445 -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. ^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^32^^>>path:#sdfootnote32sym||name="sdfootnote32anc"]](%%)^^
456 +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. ^^[[^^32^^>>path:#sdfootnote32sym||name="sdfootnote32anc"]]^^
446 446  
447 447  In the direction from SDMX to VTL it is allowed to omit the value of one or more
448 448  
... ... @@ -470,12 +470,12 @@
470 470  
471 471  Dataflow DF2(1.0.0) having the Dimensions TIME_PERIOD, INDICATOR, and COUNTRY and that such a programmer finds it convenient to calculate separately the parts of DF2(1.0.0) that have different combinations of values for INDICATOR and COUNTRY:
472 472  
473 -* each part is calculated as a VTL derived Data Set, result of a dedicated VTL Transformation; ^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^33^^>>path:#sdfootnote33sym||name="sdfootnote33anc"]](%%)^^
474 -* the data structure of all these VTL Data Sets has the TIME_PERIOD identifier and does not have the INDICATOR and COUNTRY identifiers.^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^34^^>>path:#sdfootnote34sym||name="sdfootnote34anc"]](%%)^^
484 +* each part is calculated as a VTL derived Data Set, result of a dedicated VTL Transformation; ^^[[^^33^^>>path:#sdfootnote33sym||name="sdfootnote33anc"]]^^
485 +* the data structure of all these VTL Data Sets has the TIME_PERIOD identifier and does not have the INDICATOR and COUNTRY identifiers.^^[[^^34^^>>path:#sdfootnote34sym||name="sdfootnote34anc"]]^^
475 475  
476 -Under these hypothesis, such derived VTL Data Sets can be mapped to DF2(1.0.0) by declaring the DimensionComponents INDICATOR and COUNTRY as mapping dimensions^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^35^^>>path:#sdfootnote35sym||name="sdfootnote35anc"]](%%)^^.
487 +Under these hypothesis, such derived VTL Data Sets can be mapped to DF2(1.0.0) by declaring the DimensionComponents INDICATOR and COUNTRY as mapping dimensions^^[[^^35^^>>path:#sdfootnote35sym||name="sdfootnote35anc"]]^^.
477 477  
478 -The corresponding VTL Transformations, assuming that the result needs to be persistent, would be of this kind:^^ [[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^36^^>>path:#sdfootnote36sym||name="sdfootnote36anc"]](%%)^^
489 +The corresponding VTL Transformations, assuming that the result needs to be persistent, would be of this kind:^^ [[^^36^^>>path:#sdfootnote36sym||name="sdfootnote36anc"]]^^
479 479  
480 480  ‘DF2(1.0.0)/INDICATORvalue.COUNTRYvalue’ <- expression
481 481  
... ... @@ -531,9 +531,9 @@
531 531  
532 532  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
533 533  
534 -DF2bis_GDPPERCAPITA_USA and so on) by adding the identifiers INDICATOR and COUNTRY with the desired values (//INDICATORvalue// and //COUNTRYvalue)//. Finally, all these non-persistent Data Sets are united and give the final result DF2(1.0)^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^37^^>>path:#sdfootnote37sym||name="sdfootnote37anc"]](%%)^^, which can be mapped one-to-one to the homonymous SDMX Dataflow having the dimension components TIME_PERIOD, INDICATOR and COUNTRY.
545 +DF2bis_GDPPERCAPITA_USA and so on) by adding the identifiers INDICATOR and COUNTRY with the desired values (//INDICATORvalue// and //COUNTRYvalue)//. Finally, all these non-persistent Data Sets are united and give the final result DF2(1.0)^^[[^^37^^>>path:#sdfootnote37sym||name="sdfootnote37anc"]]^^, which can be mapped one-to-one to the homonymous SDMX Dataflow having the dimension components TIME_PERIOD, INDICATOR and COUNTRY.
535 535  
536 -Therefore, mapping different VTL datasets having the same data structure to different parts of a SDMX Dataflow, i.e. in the direction from VTL to SDMX, through the ordered concatenation notation is equivalent to a proper use of the operators “calc” and “union” on such datasets. ^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^38^^>>path:#sdfootnote38sym||name="sdfootnote38anc"]](%%)[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^39^^>>path:#sdfootnote39sym||name="sdfootnote39anc"]](%%)^^
547 +Therefore, mapping different VTL datasets having the same data structure to different parts of a SDMX Dataflow, i.e. in the direction from VTL to SDMX, through the ordered concatenation notation is equivalent to a proper use of the operators “calc” and “union” on such datasets. ^^[[^^38^^>>path:#sdfootnote38sym||name="sdfootnote38anc"]][[^^39^^>>path:#sdfootnote39sym||name="sdfootnote39anc"]]^^
537 537  
538 538  It is worth noting that in the direction from VTL to SDMX it is mandatory to specify the value for every Dimension on which the mapping is based (in other word, in the name of the calculated VTL dataset is __not__ possible to omit the value of some of the Dimensions).
539 539  
... ... @@ -560,13 +560,13 @@
560 560  DimensionComponent, Measure, DataAttribute)
561 561  )))
562 562  |**Described Value Domain**|(((
563 -non-enumerated** &nbsp;&nbsp;&nbsp;Representation**
574 +non-enumerated** &nbsp;&nbsp;&nbsp;Representation**
564 564  
565 565  (having Facets / ExtendedFacets, see the Structure Pattern in the Base Package)
566 566  )))
567 567  |**Value**|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
568 -| |(((
569 -to a valid **value &nbsp;&nbsp;&nbsp;**(for non-enumerated** &nbsp;&nbsp;&nbsp;**
579 +||(((
580 +to a valid **value &nbsp;&nbsp;&nbsp;**(for non-enumerated** &nbsp;&nbsp;&nbsp;**
570 570  
571 571  Representations)
572 572  )))
... ... @@ -577,7 +577,7 @@
577 577  
578 578  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).
579 579  
580 -Another difference consists in the fact that all Value Domains are considered as identifiable objects in VTL either if enumerated or not, while in SDMX the Codelist (corresponding to a VTL enumerated Value Domain) is identifiable, while the SDMX non-enumerated Representation (corresponding to a VTL non-enumerated Value Domain) is not identifiable. As a consequence, the definition of the VTL Rulesets, which in VTL can refer either to enumerated or non-enumerated value domains, in SDMX can refer only to enumerated Value Domains (i.e. to SDMX Codelists). As for the mapping between VTL variables and SDMX Concepts, it should be noted that these artefacts do not coincide perfectly. In fact, the VTL variables are represented variables, defined always on the same Value Domain (“Representation” in SDMX) independently of the data set / data structure in which they appear^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^40^^>>path:#sdfootnote40sym||name="sdfootnote40anc"]](%%)^^, while the SDMX Concepts can have different Representations in different DataStructures.^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^41^^>>path:#sdfootnote41sym||name="sdfootnote41anc"]](%%)^^ This means that one SDMX Concept can correspond to many VTL Variables, one for each representation the Concept has.
591 +Another difference consists in the fact that all Value Domains are considered as identifiable objects in VTL either if enumerated or not, while in SDMX the Codelist (corresponding to a VTL enumerated Value Domain) is identifiable, while the SDMX non-enumerated Representation (corresponding to a VTL non-enumerated Value Domain) is not identifiable. As a consequence, the definition of the VTL Rulesets, which in VTL can refer either to enumerated or non-enumerated value domains, in SDMX can refer only to enumerated Value Domains (i.e. to SDMX Codelists). As for the mapping between VTL variables and SDMX Concepts, it should be noted that these artefacts do not coincide perfectly. In fact, the VTL variables are represented variables, defined always on the same Value Domain (“Representation” in SDMX) independently of the data set / data structure in which they appear^^[[^^40^^>>path:#sdfootnote40sym||name="sdfootnote40anc"]]^^, while the SDMX Concepts can have different Representations in different DataStructures.^^[[^^41^^>>path:#sdfootnote41sym||name="sdfootnote41anc"]]^^ This means that one SDMX Concept can correspond to many VTL Variables, one for each representation the Concept has.
581 581  
582 582  Therefore, it is important to be aware that some VTL operations (for example the binary operations at data set level) are consistent only if the components having the same names in the operated VTL Data Sets have also the same representation (i.e. the same Value Domain as for VTL). For example, it is possible to obtain correct results from the VTL expression
583 583  
... ... @@ -819,37 +819,37 @@
819 819  binary-valued logic: {true, false})
820 820  )))|boolean
821 821  
822 -| |(% colspan="2" %)(((
833 +||(% colspan="2" %)(((
823 823  URI
824 824  
825 825  (corresponds to the XML Schema xs:anyURI; absolute or relative Uniform Resource Identifier Reference)
826 826  )))|(% colspan="2" %)string
827 -| |(% colspan="2" %)(((
838 +||(% colspan="2" %)(((
828 828  Count
829 829  
830 830  (an integer following a sequential pattern, increasing by 1 for each occurrence)
831 831  )))|(% colspan="2" %)integer
832 -| |(% colspan="2" %)(((
843 +||(% colspan="2" %)(((
833 833  InclusiveValueRange
834 834  
835 835  (decimal number within a closed interval, whose bounds are specified in the SDMX representation by the facets minValue and maxValue)
836 836  )))|(% colspan="2" %)number
837 -| |(% colspan="2" %)(((
848 +||(% colspan="2" %)(((
838 838  ExclusiveValueRange
839 839  
840 840  (decimal number within an open interval, whose bounds are specified in the SDMX representation by the facets minValue and maxValue)
841 841  )))|(% colspan="2" %)number
842 -| |(% colspan="2" %)(((
853 +||(% colspan="2" %)(((
843 843  Incremental
844 844  
845 845  (decimal number the increased by a specific interval (defined by the interval facet), which is typically enforced outside of the XML validation)
846 846  )))|(% colspan="2" %)number
847 -| |(% colspan="2" %)(((
858 +||(% colspan="2" %)(((
848 848  ObservationalTimePeriod
849 849  
850 850  (superset of StandardTimePeriod and TimeRange)
851 851  )))|(% colspan="2" %)time
852 -| |(% colspan="2" %)(((
863 +||(% colspan="2" %)(((
853 853  StandardTimePeriod
854 854  
855 855  (superset of BasicTimePeriod and
... ... @@ -856,20 +856,20 @@
856 856  
857 857  ReportingTimePeriod)
858 858  )))|(% colspan="2" %)time
859 -| |(% colspan="2" %)(((
870 +||(% colspan="2" %)(((
860 860  BasicTimePeriod
861 861  
862 862  (superset of GregorianTimePeriod and DateTime)
863 863  )))|(% colspan="2" %)date
864 -| |(% colspan="2" %)(((
875 +||(% colspan="2" %)(((
865 865  GregorianTimePeriod
866 866  
867 867  (superset of GregorianYear, GregorianYearMonth, and GregorianDay)
868 868  )))|(% colspan="2" %)date
869 -| |(% colspan="2" %)GregorianYear (YYYY)|(% colspan="2" %)date
870 -| |(% colspan="2" %)GregorianYearMonth / GregorianMonth (YYYY-MM)|(% colspan="2" %)date
871 -| |(% colspan="2" %)GregorianDay (YYYY-MM-DD)|(% colspan="2" %)date
872 -| |(% colspan="2" %)(((
880 +||(% colspan="2" %)GregorianYear (YYYY)|(% colspan="2" %)date
881 +||(% colspan="2" %)GregorianYearMonth / GregorianMonth (YYYY-MM)|(% colspan="2" %)date
882 +||(% colspan="2" %)GregorianDay (YYYY-MM-DD)|(% colspan="2" %)date
883 +||(% colspan="2" %)(((
873 873  ReportingTimePeriod
874 874  
875 875  (superset of RepostingYear, ReportingSemester,
... ... @@ -878,79 +878,79 @@
878 878  
879 879  ReportingMonth, ReportingWeek, ReportingDay)
880 880  )))|(% colspan="2" %)time_period
881 -| |(% colspan="2" %)(((
892 +||(% colspan="2" %)(((
882 882  ReportingYear
883 883  
884 884  (YYYY-A1 – 1 year period)
885 885  )))|(% colspan="2" %)time_period
886 -| |(% colspan="2" %)(((
897 +||(% colspan="2" %)(((
887 887  ReportingSemester
888 888  
889 889  (YYYY-Ss – 6 month period)
890 890  )))|(% colspan="2" %)time_period
891 -| |(% colspan="2" %)(((
902 +||(% colspan="2" %)(((
892 892  ReportingTrimester
893 893  
894 894  (YYYY-Tt – 4 month period)
895 895  )))|(% colspan="2" %)time_period
896 -| |(% colspan="2" %)(((
907 +||(% colspan="2" %)(((
897 897  ReportingQuarter
898 898  
899 899  (YYYY-Qq – 3 month period)
900 900  )))|(% colspan="2" %)time_period
901 -| |(% colspan="2" %)(((
912 +||(% colspan="2" %)(((
902 902  ReportingMonth
903 903  
904 904  (YYYY-Mmm – 1 month period)
905 905  )))|(% colspan="2" %)time_period
906 -| |(% colspan="2" %)ReportingWeek|(% colspan="2" %)time_period
907 -| |(% colspan="2" %) |(% colspan="2" %)
908 -| |(% colspan="2" %) |(% colspan="2" %)
909 -|(% colspan="2" %)(YYYY-Www – 7 day period; following ISO 8601 definition of a week in a year)|(% colspan="2" %) |
917 +||(% colspan="2" %)ReportingWeek|(% colspan="2" %)time_period
918 +||(% colspan="2" %)|(% colspan="2" %)
919 +||(% colspan="2" %)|(% colspan="2" %)
920 +|(% colspan="2" %)(YYYY-Www – 7 day period; following ISO 8601 definition of a week in a year)|(% colspan="2" %)|
910 910  |(% colspan="2" %)(((
911 911  ReportingDay
912 912  
913 913  (YYYY-Dddd – 1 day period)
914 -)))|(% colspan="2" %)time_period|
925 +)))|(% colspan="2" %)time_period|
915 915  |(% colspan="2" %)(((
916 916  DateTime
917 917  
918 918  (YYYY-MM-DDThh:mm:ss)
919 -)))|(% colspan="2" %)date|
930 +)))|(% colspan="2" %)date|
920 920  |(% colspan="2" %)(((
921 921  TimeRange
922 922  
923 923  (YYYY-MM-DD(Thh:mm:ss)?/<duration>)
924 -)))|(% colspan="2" %)time|
935 +)))|(% colspan="2" %)time|
925 925  |(% colspan="2" %)(((
926 926  Month
927 927  
928 928  (~-~-MM; speicifies a month independent of a year; e.g. February is black history month in the United States)
929 -)))|(% colspan="2" %)string|
940 +)))|(% colspan="2" %)string|
930 930  |(% colspan="2" %)(((
931 931  MonthDay
932 932  
933 933  (~-~-MM-DD; specifies a day within a month independent of a year; e.g. Christmas is December 25^^th^^; used to specify reporting year start day)
934 -)))|(% colspan="2" %)string|
945 +)))|(% colspan="2" %)string|
935 935  |(% colspan="2" %)(((
936 936  Day
937 937  
938 938  (~-~--DD; specifies a day independent of a month or year; e.g. the 15^^th^^ is payday)
939 -)))|(% colspan="2" %)string|
950 +)))|(% colspan="2" %)string|
940 940  |(% colspan="2" %)(((
941 941  Time
942 942  
943 943  (hh:mm:ss; time independent of a date; e.g. coffee break is at 10:00 AM)
944 -)))|(% colspan="2" %)string|
955 +)))|(% colspan="2" %)string|
945 945  |(% colspan="2" %)(((
946 946  Duration
947 947  
948 948  (corresponds to XML Schema xs:duration datatype)
949 -)))|(% colspan="2" %)duration|
950 -|(% colspan="2" %)XHTML|(% colspan="2" %)Metadata type – not applicable|
951 -|(% colspan="2" %)KeyValues|(% colspan="2" %)Metadata type – not applicable|
952 -|(% colspan="2" %)IdentifiableReference|(% colspan="2" %)Metadata type – not applicable|
953 -|(% colspan="2" %)DataSetReference|(% colspan="2" %)Metadata type – not applicable|
960 +)))|(% colspan="2" %)duration|
961 +|(% colspan="2" %)XHTML|(% colspan="2" %)Metadata type – not applicable|
962 +|(% colspan="2" %)KeyValues|(% colspan="2" %)Metadata type – not applicable|
963 +|(% colspan="2" %)IdentifiableReference|(% colspan="2" %)Metadata type – not applicable|
964 +|(% colspan="2" %)DataSetReference|(% colspan="2" %)Metadata type – not applicable|
954 954  
955 955  ==== Figure 14 – Mappings from SDMX data types to VTL Basic Scalar Types ====
956 956  
... ... @@ -999,13 +999,13 @@
999 999  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.
1000 1000  
1001 1001  |(% colspan="2" %)VTL special characters for the formatting masks
1002 -|(% colspan="2" %)
1013 +|(% colspan="2" %)
1003 1003  |(% colspan="2" %)Number
1004 1004  |D|one numeric digit (if the scientific notation is adopted, D is only for the mantissa)
1005 1005  |E|one numeric digit (for the exponent of the scientific notation)
1006 1006  |. (dot)|possible separator between the integer and the decimal parts.
1007 1007  |, (comma)|possible separator between the integer and the decimal parts.
1008 -| |
1019 +||
1009 1009  |(% colspan="2" %)Time and duration
1010 1010  |C|century
1011 1011  |Y|year
... ... @@ -1027,17 +1027,17 @@
1027 1027  |Day|lowercase textual representation of the month (e.g., monday)
1028 1028  |Month|First character uppercase, then lowercase textual representation of the month (e.g., January)
1029 1029  |Day|First character uppercase, then lowercase textual representation of the day using (e.g. Monday)
1030 -| |
1041 +||
1031 1031  |(% colspan="2" %)String
1032 1032  |X|any string character
1033 1033  |Z|any string character from "A" to "z"
1034 1034  |9|any string character from "0" to "9"
1035 -| |
1046 +||
1036 1036  |(% colspan="2" %)Boolean
1037 1037  |B|Boolean using "true" for True and "false" for False
1038 1038  |1|Boolean using "1" for True and "0" for False
1039 1039  |0|Boolean using "0" for True and "1" for False
1040 -| |
1051 +||
1041 1041  |(% colspan="2" %)Other qualifiers
1042 1042  |*|an arbitrary number of digits (of the preceding type)
1043 1043  |+|at least one digit (of the preceding type)
... ... @@ -1044,9 +1044,9 @@
1044 1044  |( )|optional digits (specified within the brackets)
1045 1045  |\|prefix for the special characters that must appear in the mask
1046 1046  |N|fixed number of digits used in the preceding textual representation of the month or the day
1047 -| |
1058 +||
1048 1048  
1049 -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^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^42^^>>path:#sdfootnote42sym||name="sdfootnote42anc"]](%%)^^.
1060 +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^^[[^^42^^>>path:#sdfootnote42sym||name="sdfootnote42anc"]]^^.
1050 1050  
1051 1051  === 12.4.5 Null Values ===
1052 1052  
... ... @@ -1069,5 +1069,3 @@
1069 1069  TransformationScheme.
1070 1070  
1071 1071  In case a literal is operand of a VTL Cast operation, the format specified in the Cast overrides all the possible otherwise specified formats.
1072 -
1073 -{{putFootnotes/}}