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... ... @@ -2,9 +2,10 @@
2 2  {{toc/}}
3 3  {{/box}}
4 4  
5 -== 12.1 Introduction ==
5 +1.
6 +11. 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:
8 +The Validation and Transformation Language (VTL) supports the definition of Transformations, which are algorithms to calculate new data starting from already existing ones[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[1~]^^>>path:#_ftn1]](%%). 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);
... ... @@ -12,30 +12,33 @@
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).
16 +The VTL language can be applied to SDMX artefacts by mapping the SDMX IM model artefacts to the model artefacts that VTL can manipulate[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[2~]^^>>path:#_ftn2]](%%). 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 Transformation (nameable artefact). Each Transformation assigns the outcome of the evaluation of a VTL expression to a result.
18 18  
19 19  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.
20 20  
21 -== 12.2 References to SDMX artefacts from VTL statements ==
22 -=== 12.2.1 Introduction ===
22 +1.
23 +11. References to SDMX artefacts from VTL statements
24 +111. Introduction
23 23  
24 24  The VTL can manipulate SDMX artefacts (or objects) by referencing them through predefined conventional names (aliases).
25 25  
26 26  The alias of an SDMX artefact can be its URN (Universal Resource Name), an abbreviation of its URN or another user-defined name.
27 27  
28 -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.
30 +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[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[3~]^^>>path:#_ftn3]](%%) or User Defined Operators[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[4~]^^>>path:#_ftn4]](%%) to reference SDMX artefacts. A VtlMappingScheme is a container for zero or more VtlMapping.
29 29  
30 30  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.
31 31  
32 32  The references through the URN and the abbreviated URN are described in the following paragraphs.
33 33  
34 -=== 12.2.2 References through the URN ===
36 +1.
37 +11.
38 +111. References through the URN
35 35  
36 36  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.
37 37  
38 -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}}(% style="font-size:12px" %) (%%)is the concatenation of the following parts, separated by special symbols like dot, equal, asterisk, comma, and parenthesis:
42 +The SDMX URN[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[5~]^^>>path:#_ftn5]](%%) is the concatenation of the following parts, separated by special symbols like dot, equal, asterisk, comma, and parenthesis:
39 39  
40 40  * SDMXprefix
41 41  * SDMX-IM-package-name
... ... @@ -43,7 +43,7 @@
43 43  * agency-id
44 44  * maintainedobject-id
45 45  * maintainedobject-version
46 -* container-object-id{{footnote}}The container-object-id can repeat and may not be present.{{/footnote}}
50 +* container-object-id [[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[6~]^^>>path:#_ftn6]]
47 47  * object-id
48 48  
49 49  The generic structure of the URN is the following:
... ... @@ -60,7 +60,7 @@
60 60  
61 61  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).
62 62  
63 -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:
67 +The maintainedobject-id is the name of the maintained object which the artefact belongs to, and in case the artefact itself is maintainable[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[7~]^^>>path:#_ftn7]](%%), coincides with the name of the artefact. Therefore the maintainedobject-id depends on the class of the artefact:
64 64  
65 65  * if the artefact is a Dataflow, which is a maintainable class, the maintainedobject-id is the Dataflow name (dataflow-id);
66 66  * if the artefact is a Dimension, Measure, TimeDimension or DataAttribute, which are not maintainable and belong to the
... ... @@ -82,7 +82,7 @@
82 82  
83 83  * if the artefact is a Concept (the object-id is the name of the Concept)
84 84  
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{{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}}:
89 +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[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[8~]^^>>path:#_ftn8]](%%):
86 86  
87 87  'urn:sdmx:org.sdmx.infomodel.datastructure.Dataflow=AG:DFR(1.0.0)' <-
88 88  
... ... @@ -90,7 +90,9 @@
90 90  
91 91  'urn:sdmx:org.sdmx.infomodel.datastructure.Dataflow=AG:DF2(1.0.0)'
92 92  
93 -=== 12.2.3 Abbreviation of the URN ===
97 +1.
98 +11.
99 +111. Abbreviation of the URN
94 94  
95 95  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.
96 96  
... ... @@ -99,10 +99,14 @@
99 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.
100 100  * 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:
101 101  ** "datastructure" for the classes Dataflow, Dimension, TimeDimension, Measure, DataAttribute, o "conceptscheme" for the class Concept, o "codelist" for the class Codelist.
102 -* 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}}.
103 -* 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).
108 +* 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[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[9~]^^>>path:#_ftn9]](%%), the SDMX class can be deduced from the mapping rules between VTL and SDMX (see the section "Mapping between VTL and SDMX" hereinafter)[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[10~]^^>>path:#_ftn10]](%%).
109 +* 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[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[11~]^^>>path:#_ftn11]](%%). 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).
104 104  * 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;
105 -** 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;
111 +** if the referenced artefact is a Dimension, TimeDimension, Measure,
112 +
113 +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;
114 +
115 +*
106 106  ** 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;
107 107  ** if the referenced artefact is a Codelist, which is a maintainable class, the maintainedobject-id is the codelist-id and obviously cannot be omitted.
108 108  * 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.
... ... @@ -123,7 +123,7 @@
123 123  
124 124  DFR := DF1 + DF2
125 125  
126 -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. 19 Single quotes are not needed in this case because CL_FREQ is a VTL regular name.{{/footnote}}:
136 +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[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[12~]^^>>path:#_ftn12]](%%):
127 127  
128 128  'urn:sdmx:org.sdmx.infomodel.codelist.Codelist=AG:CL_FREQ(1.0.0)'
129 129  
... ... @@ -141,7 +141,7 @@
141 141  
142 142  SECTOR
143 143  
144 -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}}:
154 +For example, the Transformation for renaming the component SECTOR of the Dataflow DF1 into SEC can be written as[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[13~]^^>>path:#_ftn13]](%%):
145 145  
146 146  'DFR(1.0.0)' := 'DF1(1.0.0)' [rename SECTOR to SEC]
147 147  
... ... @@ -161,36 +161,43 @@
161 161  
162 162  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).
163 163  
164 -=== 12.2.4 User-defined alias ===
174 +1.
175 +11.
176 +111. User-defined alias
165 165  
166 166  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.
167 167  
168 168  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).
169 169  
170 -=== 12.2.5 References to SDMX artefacts from VTL Rulesets ===
182 +1.
183 +11.
184 +111. References to SDMX artefacts from VTL Rulesets
171 171  
172 172  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.
173 173  
174 174  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.
175 175  
176 -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}}.
190 +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[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[14~]^^>>path:#_ftn14]](%%).
177 177  
178 -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}}
192 +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.[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[15~]^^>>path:#_ftn15]]
179 179  
180 180  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.
181 181  
182 -== 12.3 Mapping between SDMX and VTL artefacts ==
183 -=== 12.3.1. When the mapping occurs ===
196 +1.
197 +11. Mapping between SDMX and VTL artefacts
198 +111. When the mapping occurs
184 184  
185 185  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 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.
186 186  
187 -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 nonpersistent calculation is disseminated through SDMX tools (like an inquiry tool).{{/footnote}}.
202 +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[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[16~]^^>>path:#_ftn16]](%%).
188 188  
189 189  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).
190 190  
191 -=== 12.3.2 General mapping of VTL and SDMX data structures ===
206 +1.
207 +11.
208 +111. General mapping of VTL and SDMX data structures
192 192  
193 -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}}.
210 +This section makes reference to the VTL "Model for data and their structure"[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^~[17~]^^>>path:#_ftn17]](%%) and the correspondent SDMX "Data Structure Definition"{{footnote}}See the SDMX Standards Section 2 – Information Model{{/footnote}}.
194 194  
195 195  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}}
196 196  
... ... @@ -204,9 +204,11 @@
204 204  
205 205  The possible mapping options are described in more detail in the following sections.
206 206  
207 -=== 12.3.2 Mapping from SDMX to VTL data structures ===
224 +1.
225 +11.
226 +111. Mapping from SDMX to VTL data structures
208 208  
209 -==== 12.3.3.1 Basic Mapping ====
228 +**12.3.3.1 Basic Mapping**
210 210  
211 211  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.
212 212  
... ... @@ -222,7 +222,7 @@
222 222  
223 223  With the Basic mapping, one SDMX observation^^27^^ generates one VTL data point.
224 224  
225 -==== 12.3.3.2 Pivot Mapping ====
244 +**12.3.3.2 Pivot Mapping**
226 226  
227 227  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.
228 228  
... ... @@ -253,6 +253,7 @@
253 253  |DataAttribute not depending on the MeasureDimension|Attribute
254 254  |DataAttribute depending on the MeasureDimension|(((
255 255  One Attribute for each Code of the
275 +
256 256  SDMX MeasureDimension
257 257  )))
258 258  
... ... @@ -265,10 +265,13 @@
265 265  
266 266  Identifiers, (time) Identifier and Attributes.
267 267  
268 -* 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
288 +* 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
289 +
290 +Cj
291 +
269 269  * 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
270 270  
271 -==== 12.3.3.3 From SDMX DataAttributes to VTL Measures ====
294 +**12.3.3.3 From SDMX DataAttributes to VTL Measures**
272 272  
273 273  * 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
274 274  
... ... @@ -278,9 +278,11 @@
278 278  
279 279  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.
280 280  
281 -=== 12.3.4 Mapping from VTL to SDMX data structures ===
304 +1.
305 +11.
306 +111. Mapping from VTL to SDMX data structures
282 282  
283 -==== 12.3.4.1 Basic Mapping ====
308 +**12.3.4.1 Basic Mapping**
284 284  
285 285  The main mapping method **from VTL to SDMX** is called **Basic **mapping as well.
286 286  
... ... @@ -304,7 +304,7 @@
304 304  
305 305  As said, the resulting SDMX definitions must be compliant with the SDMX consistency rules. For example, the SDMX DSD must have the AttributeRelationship for the DataAttributes, which does not exist in VTL.
306 306  
307 -==== 12.3.4.2 Unpivot Mapping ====
332 +**12.3.4.2 Unpivot Mapping**
308 308  
309 309  An alternative mapping method from VTL to SDMX is the **Unpivot **mapping.
310 310  
... ... @@ -340,7 +340,7 @@
340 340  
341 341  In any case, the resulting SDMX definitions must be compliant with the SDMX consistency rules. For example, the possible Codes of the SDMX MeasureDimension need to be listed in a SDMX Codelist, with proper id, agency and version; moreover, the SDMX DSD must have the AttributeRelationship for the DataAttributes, which does not exist in VTL.
342 342  
343 -==== 12.3.4.3 From VTL Measures to SDMX Data Attributes ====
368 +**12.3.4.3 From VTL Measures to SDMX Data Attributes**
344 344  
345 345  More than all for the multi-measure VTL structures (having more than one Measure Component), it may happen that the Measures of the VTL Data Structure need to be managed as DataAttributes in SDMX. Therefore, a third mapping method consists in transforming some VTL measures in a corresponding SDMX Measures and all the other VTL Measures in SDMX DataAttributes. This method is called M2A (“M2A” stands for “Measures to DataAttributes”).
346 346  
... ... @@ -357,7 +357,9 @@
357 357  
358 358  Even in this case, the resulting SDMX definitions must be compliant with the SDMX consistency rules. For example, the SDMX DSD must have the attributeRelationship for the DataAttributes, which does not exist in VTL.
359 359  
360 -=== 12.3.5 Declaration of the mapping methods between data structures ===
385 +1.
386 +11.
387 +111. Declaration of the mapping methods between data structures
361 361  
362 362  In order to define and understand properly VTL Transformations, the applied mapping methods must be specified in the SDMX structural metadata. If the default mapping method (Basic) is applied, no specification is needed.
363 363  
... ... @@ -367,10 +367,14 @@
367 367  
368 368  The VtlMappingScheme is a container for zero or more VtlDataflowMapping (it may contain also mappings towards artefacts other than dataflows).
369 369  
370 -=== 12.3.6 Mapping dataflow subsets to distinct VTL Data Sets ===
397 +1.
398 +11.
399 +111. Mapping dataflow subsets to distinct VTL Data Sets
371 371  
372 -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).
401 +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
373 373  
403 +(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).
404 +
374 374  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.{{footnote}}A typical example of this kind is the validation, and more in general the manipulation, of individual time series belonging to the same Dataflow, identifiable through the DimensionComponents of the Dataflow except the TimeDimension. The coding of these kind of operations might be simplified by mapping distinct time series (i.e. different parts of a SDMX Dataflow) to distinct VTL Data Sets.{{/footnote}}
375 375  
376 376  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.{{footnote}}Please note that this kind of mapping is only an option at disposal of the definer of VTL Transformations; in fact it remains always possible to manipulate the needed parts of SDMX Dataflows by means of VTL operators (e.g. “sub”, “filter”, “calc”, “union” …), maintaining a mapping one-to-one between SDMX Dataflows and VTL Data Sets.{{/footnote}}
... ... @@ -463,10 +463,13 @@
463 463  Some examples follow, for some specific values of INDICATOR and COUNTRY:
464 464  
465 465  ‘DF2(1.0.0)/GDPPERCAPITA.USA’ <- expression11; ‘DF2(1.0.0)/GDPPERCAPITA.CANADA’ <- expression12;
497 +
466 466  … … …
467 467  
468 468  ‘DF2(1.0.0)/POPGROWTH.USA’ <- expression21;
501 +
469 469  ‘DF2(1.0.0)/POPGROWTH.CANADA’ <- expression22;
503 +
470 470  … … …
471 471  
472 472  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:
... ... @@ -473,9 +473,13 @@
473 473  
474 474  VTL dataset   INDICATOR value COUNTRY value
475 475  
510 +
476 476  ‘DF2(1.0.0)/GDPPERCAPITA.USA’ GDPPERCAPITA USA
512 +
477 477  ‘DF2(1.0.0)/GDPPERCAPITA.CANADA’ GDPPERCAPITA CANADA … … …
514 +
478 478  ‘DF2(1.0.0)/POPGROWTH.USA’  POPGROWTH USA
516 +
479 479  ‘DF2(1.0.0)/POPGROWTH.CANADA’ POPGROWTH CANADA
480 480  
481 481  … … …
... ... @@ -483,15 +483,25 @@
483 483  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:
484 484  
485 485  DF2bis_GDPPERCAPITA_USA := ‘DF2(1.0.0)/GDPPERCAPITA.USA’ [calc identifier INDICATOR := ”GDPPERCAPITA”, identifier COUNTRY := ”USA”];
524 +
486 486  DF2bis_GDPPERCAPITA_CANADA := ‘DF2(1.0.0)/GDPPERCAPITA.CANADA’ [calc identifier INDICATOR:=”GDPPERCAPITA”, identifier COUNTRY:=”CANADA”]; … … …
526 +
487 487  DF2bis_POPGROWTH_USA := ‘DF2(1.0.0)/POPGROWTH.USA’
528 +
488 488  [calc identifier INDICATOR := ”POPGROWTH”, identifier COUNTRY := ”USA”];
530 +
489 489  DF2bis_POPGROWTH_CANADA’ := ‘DF2(1.0.0)/POPGROWTH.CANADA’ [calc identifier INDICATOR := ”POPGROWTH”, identifier COUNTRY := ”CANADA”]; … … …
532 +
490 490  DF2(1.0) <- UNION  (DF2bis_GDPPERCAPITA_USA’,
534 +
491 491  DF2bis_GDPPERCAPITA_CANADA’,
536 +
492 492  … ,
538 +
493 493  DF2bis_POPGROWTH_USA’,
540 +
494 494  DF2bis_POPGROWTH_CANADA’
542 +
495 495  …);
496 496  
497 497  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 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){{footnote}}The result is persistent in this example but it can be also non persistent if needed.{{/footnote}}, which can be mapped one-to-one to the homonymous SDMX Dataflow having the dimension components TIME_PERIOD, INDICATOR and COUNTRY.
... ... @@ -500,7 +500,9 @@
500 500  
501 501  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).
502 502  
503 -=== 12.3.7 Mapping variables and value domains between VTL and SDMX ===
551 +1.
552 +11.
553 +111. Mapping variables and value domains between VTL and SDMX
504 504  
505 505  With reference to the VTL “model for Variables and Value domains”, the following additional mappings have to be considered:
506 506  
... ... @@ -509,6 +509,7 @@
509 509  |**Represented Variable**|**Concept** with a definite Representation
510 510  |**Value Domain**|(((
511 511  **Representation** (see the Structure
562 +
512 512  Pattern in the Base Package)
513 513  )))
514 514  |**Enumerated Value Domain / Code List**|**Codelist**
... ... @@ -515,6 +515,7 @@
515 515  |**Code**|**Code** (for enumerated DimensionComponent, Measure, DataAttribute)
516 516  |**Described Value Domain**|(((
517 517  non-enumerated** Representation**
569 +
518 518  (having Facets / ExtendedFacets, see the Structure Pattern in the Base Package)
519 519  )))
520 520  |**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
... ... @@ -538,8 +538,9 @@
538 538  
539 539  It remains up to the SDMX-VTL definer also the assurance of the consistency between a VTL Ruleset defined on Variables and the SDMX Components on which the Ruleset is applied. In fact, a VTL Ruleset is expressed by means of the values of the Variables (i.e. SDMX Concepts), i.e. assuming definite representations for them (e.g. ISOalpha-3 for country). If the Ruleset is applied to SDMX Components that have the same name of the Concept they refer to but different representations (e.g. ISO-alpha-2 for country), the Ruleset cannot work properly.
540 540  
541 -== 12.4 Mapping between SDMX and VTL Data Types ==
542 -=== 12.4.1 VTL Data types ===
593 +1.
594 +11. Mapping between SDMX and VTL Data Types
595 +111. VTL Data types
543 543  
544 544  According to the VTL User Guide the possible operations in VTL depend on the data types of the artefacts. For example, numbers can be multiplied but text strings cannot. In the VTL Transformations, the compliance between the operators and the data types of their operands is statically checked, i.e., violations result in compile-time errors.
545 545  
... ... @@ -547,15 +547,17 @@
547 547  
548 548  [[image:1750067055028-964.png]]
549 549  
550 -**Figure 22 – VTL Data Types**
603 +==== Figure 22 – VTL Data Types ====
551 551  
552 552  The VTL scalar types are in turn subdivided in basic scalar types, which are elementary (not defined in term of other data types) and Value Domain and Set scalar types, which are defined in terms of the basic scalar types.
553 553  
554 554  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):
555 555  
556 -**Figure 23 – VTL Basic Scalar Types**
609 +==== Figure 23 – VTL Basic Scalar Types ====
557 557  
558 -=== 12.4.2 VTL basic scalar types and SDMX data types ===
611 +1.
612 +11.
613 +111. VTL basic scalar types and SDMX data types
559 559  
560 560  The VTL assumes that a basic scalar type has a unique internal representation and can have more external representations.
561 561  
... ... @@ -573,7 +573,9 @@
573 573  
574 574  The opposite conversion, i.e. from VTL to SDMX, happens when a VTL result, i.e. a VTL Data Set output of a Transformation, must become a SDMX artefact (or part of it). The values of the VTL result must be converted into the desired (SDMX) external representations (data types) of the SDMX artefact.
575 575  
576 -=== 12.4.3 Mapping SDMX data types to VTL basic scalar types ===
631 +1.
632 +11.
633 +111. Mapping SDMX data types to VTL basic scalar types
577 577  
578 578  The following table describes the default mapping for converting from the SDMX data types to the VTL basic scalar types.
579 579  
... ... @@ -580,6 +580,7 @@
580 580  |SDMX data type (BasicComponentDataType)|Default VTL basic scalar type
581 581  |(((
582 582  String
640 +
583 583  (string allowing any character)
584 584  )))|string
585 585  |(((
... ... @@ -589,6 +589,7 @@
589 589  )))|string
590 590  |(((
591 591  AlphaNumeric
650 +
592 592  (string which only allows A-z and 0-9)
593 593  )))|string
594 594  |(((
... ... @@ -598,70 +598,89 @@
598 598  )))|string
599 599  |(((
600 600  BigInteger
660 +
601 601  (corresponds to XML Schema xs:integer datatype; infinite set of integer values)
602 602  )))|integer
603 603  |(((
604 604  Integer
665 +
605 605  (corresponds to XML Schema xs:int datatype; between -2147483648 and +2147483647
667 +
606 606  (inclusive))
607 607  )))|integer
608 608  |(((
609 609  Long
672 +
610 610  (corresponds to XML Schema xs:long datatype; between -9223372036854775808 and
674 +
611 611  +9223372036854775807 (inclusive))
612 612  )))|integer
613 613  |(((
614 614  Short
679 +
615 615  (corresponds to XML Schema xs:short datatype; between -32768 and -32767 (inclusive))
616 616  )))|integer
617 617  |Decimal (corresponds to XML Schema xs:decimal datatype; subset of real numbers that can be represented as decimals)|number
618 618  |(((
619 619  Float
685 +
620 620  (corresponds to XML Schema xs:float datatype; patterned after the IEEE single-precision 32-bit floating point type)
621 621  )))|number
622 622  |(((
623 623  Double
690 +
624 624  (corresponds to XML Schema xs:double datatype; patterned after the IEEE double-precision 64-bit floating point type)
625 625  )))|number
626 626  |(((
627 627  Boolean
695 +
628 628  (corresponds to the XML Schema xs:boolean datatype; support the mathematical concept of
697 +
629 629  binary-valued logic: {true, false})
630 630  )))|boolean
631 631  |(((
632 632  URI
702 +
633 633  (corresponds to the XML Schema xs:anyURI; absolute or relative Uniform Resource Identifier Reference)
634 634  )))|string
635 635  |(((
636 636  Count
707 +
637 637  (an integer following a sequential pattern, increasing by 1 for each occurrence)
638 638  )))|integer
639 639  |(((
640 640  InclusiveValueRange
712 +
641 641  (decimal number within a closed interval, whose bounds are specified in the SDMX representation by the facets minValue and maxValue)
642 642  )))|number
643 643  |(((
644 644  ExclusiveValueRange
717 +
645 645  (decimal number within an open interval, whose bounds are specified in the SDMX representation by the facets minValue and maxValue)
646 646  )))|number
647 647  |(((
648 648  Incremental
722 +
649 649  (decimal number the increased by a specific interval (defined by the interval facet), which is typically enforced outside of the XML validation)
650 650  )))|number
651 651  |(((
652 652  ObservationalTimePeriod
727 +
653 653  (superset of StandardTimePeriod and TimeRange)
654 654  )))|time
655 655  |(((
656 656  StandardTimePeriod
732 +
657 657  (superset of BasicTimePeriod and ReportingTimePeriod)
658 658  )))|time
659 659  |(((
660 660  BasicTimePeriod
737 +
661 661  (superset of GregorianTimePeriod and DateTime)
662 662  )))|date
663 663  |(((
664 664  GregorianTimePeriod
742 +
665 665  (superset of GregorianYear, GregorianYearMonth, and GregorianDay)
666 666  )))|date
667 667  |GregorianYear (YYYY)|date
... ... @@ -669,26 +669,32 @@
669 669  |GregorianDay (YYYY-MM-DD)|date
670 670  |(((
671 671  ReportingTimePeriod
750 +
672 672  (superset of RepostingYear, ReportingSemester, ReportingTrimester, ReportingQuarter, ReportingMonth, ReportingWeek, ReportingDay)
673 673  )))|time_period
674 674  |(((
675 675  ReportingYear
755 +
676 676  (YYYY-A1 – 1 year period)
677 677  )))|time_period
678 678  |(((
679 679  ReportingSemester
760 +
680 680  (YYYY-Ss – 6 month period)
681 681  )))|time_period
682 682  |(((
683 683  ReportingTrimester
765 +
684 684  (YYYY-Tt – 4 month period)
685 685  )))|time_period
686 686  |(((
687 687  ReportingQuarter
770 +
688 688  (YYYY-Qq – 3 month period)
689 689  )))|time_period
690 690  |(((
691 691  ReportingMonth
775 +
692 692  (YYYY-Mmm – 1 month period)
693 693  )))|time_period
694 694  |ReportingWeek|time_period
... ... @@ -695,34 +695,42 @@
695 695  | (YYYY-Www – 7 day period; following ISO 8601 definition of a week in a year)|
696 696  |(((
697 697  ReportingDay
782 +
698 698  (YYYY-Dddd – 1 day period)
699 699  )))|time_period
700 700  |(((
701 701  DateTime
787 +
702 702  (YYYY-MM-DDThh:mm:ss)
703 703  )))|date
704 704  |(((
705 705  TimeRange
792 +
706 706  (YYYY-MM-DD(Thh:mm:ss)?/<duration>)
707 707  )))|time
708 708  |(((
709 709  Month
797 +
710 710  (~-~-MM; speicifies a month independent of a year; e.g. February is black history month in the United States)
711 711  )))|string
712 712  |(((
713 713  MonthDay
802 +
714 714  (~-~-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)
715 715  )))|string
716 716  |(((
717 717  Day
807 +
718 718  (~-~--DD; specifies a day independent of a month or year; e.g. the 15^^th^^ is payday)
719 719  )))|string
720 720  |(((
721 721  Time
812 +
722 722  (hh:mm:ss; time independent of a date; e.g. coffee break is at 10:00 AM)
723 723  )))|string
724 724  |(((
725 725  Duration
817 +
726 726  (corresponds to XML Schema xs:duration datatype)
727 727  )))|duration
728 728  |XHTML|Metadata type – not applicable
... ... @@ -730,20 +730,27 @@
730 730  |IdentifiableReference|Metadata type – not applicable
731 731  |DataSetReference|Metadata type – not applicable
732 732  
733 -**Figure 14 – Mappings from SDMX data types to VTL Basic Scalar Types**
825 +додол
734 734  
827 +==== Figure 14 – Mappings from SDMX data types to VTL Basic Scalar Types ====
828 +
735 735  When VTL takes in input SDMX artefacts, it is assumed that a type conversion according to the table above always happens. In case a different VTL basic scalar type is desired, it can be achieved in the VTL program taking in input the default VTL basic scalar type above and applying to it the VTL type conversion features (see the implicit and explicit type conversion and the "cast" operator in the VTL Reference Manual).
736 736  
737 -=== 12.4.4 Mapping VTL basic scalar types to SDMX data types ===
831 +1.
832 +11.
833 +111. Mapping VTL basic scalar types to SDMX data types
738 738  
739 739  The following table describes the default conversion from the VTL basic scalar types to the SDMX data types .
740 740  
741 741  |(((
742 742  VTL basic
839 +
743 743  scalar type
744 744  )))|(((
745 745  Default SDMX data type
843 +
746 746  (BasicComponentDataType
845 +
747 747  )
748 748  )))|Default output format
749 749  |String|String|Like XML (xs:string)
... ... @@ -753,15 +753,17 @@
753 753  |Time|StandardTimePeriod|<date>/<date> (as defined above)
754 754  |time_period|(((
755 755  ReportingTimePeriod
855 +
756 756  (StandardReportingPeriod)
757 757  )))|(((
758 758   YYYY-Pppp
859 +
759 759  (according to SDMX )
760 760  )))
761 761  |Duration|Duration|Like XML (xs:duration) PnYnMnDTnHnMnS
762 762  |Boolean|Boolean|Like XML (xs:boolean) with the values "true" or "false"
763 763  
764 -**Figure 14 – Mappings from SDMX data types to VTL Basic Scalar Types**
865 +==== Figure 14 – Mappings from SDMX data types to VTL Basic Scalar Types ====
765 765  
766 766  In case a different default conversion is desired, it can be achieved through the CustomTypeScheme and CustomType artefacts (see also the section
767 767  
... ... @@ -819,13 +819,17 @@
819 819  
820 820  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}}.
821 821  
822 -=== 12.4.3 Null Values ===
923 +1.
924 +11.
925 +111. Null Values
823 823  
824 824  In the conversions from SDMX to VTL it is assumed by default that a missing value in SDMX becomes a NULL in VTL. After the conversion, the NULLs can be manipulated through the proper VTL operators.
825 825  
826 826  On the other side, the VTL programs can produce in output NULL values for Measures and Attributes (Null values are not allowed in the Identifiers). In the conversion from VTL to SDMX, it is assumed that a NULL in VTL becomes a missing value in SDMX. In the conversion from VTL to SDMX, the default assumption can be overridden, separately for each VTL basic scalar type, by specifying which the value that represents the NULL in SDMX is. This can be specified in the attribute "nullValue" of the CustomType artefact (see also the section Transformations and Expressions of the SDMX information model). A CustomType belongs to a CustomTypeScheme, which can be referenced by one or more TransformationScheme (i.e. VTL programs). The overriding assumption is applied for all the SDMX Dataflows calculated in the TransformationScheme.
827 827  
828 -=== 12.4.5 Format of the literals used in VTL Transformations ===
931 +1.
932 +11.
933 +111. Format of the literals used in VTL Transformations
829 829  
830 830  The VTL programs can contain literals, i.e. specific values of certain data types written directly in the VTL definitions or expressions. The VTL does not prescribe a specific format for the literals and leave the specific VTL systems and the definers of VTL Transformations free of using their preferred formats.
831 831  
... ... @@ -839,6 +839,42 @@
839 839  
840 840  In case a literal is operand of a VTL Cast operation, the format specified in the Cast overrides all the possible otherwise specified formats.
841 841  
947 +
842 842  ----
843 843  
950 +[[~[1~]>>path:#_ftnref1]] 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>>url:https://sdmx.org/]][[.>>url:https://sdmx.org/]]
951 +
952 +[[~[2~]>>path:#_ftnref2]] 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
953 +
954 +[[~[3~]>>path:#_ftnref3]] See also the section "VTL-DL Rulesets" in the VTL Reference Manual.
955 +
956 +[[~[4~]>>path:#_ftnref4]] 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.
957 +
958 +[[~[5~]>>path:#_ftnref5]] 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)").
959 +
960 +[[~[6~]>>path:#_ftnref6]] The container-object-id can repeat and may not be present.
961 +
962 +[[~[7~]>>path:#_ftnref7]] i.e., the artefact belongs to a maintainable class
963 +
964 +[[~[8~]>>path:#_ftnref8]] 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.
965 +
966 +[[~[9~]>>path:#_ftnref9]] For the syntax of the VTL operators see the VTL Reference Manual
967 +
968 +[[~[10~]>>path:#_ftnref10]] 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.
969 +
970 +[[~[11~]>>path:#_ftnref11]] 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)
971 +
972 +[[~[12~]>>path:#_ftnref12]] Single quotes are needed because this reference is not a VTL regular name. ^^19^^ Single quotes are not needed in this case because CL_FREQ is a VTL regular name.
973 +
974 +[[~[13~]>>path:#_ftnref13]] The result DFR(1.0.0) is be equal to DF1(1.0.0) save that the component SECTOR is called SEC
975 +
976 +[[~[14~]>>path:#_ftnref14]] Rulesets of this kind cannot be reused when the referenced Concept has a different representation.
977 +
978 +[[~[15~]>>path:#_ftnref15]] See also the section "VTL-DL Rulesets" in the VTL Reference Manual.
979 +
980 +[[~[16~]>>path:#_ftnref16]] 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 nonpersistent calculation is disseminated through SDMX tools (like an inquiry tool).
981 +
982 +[[~[17~]>>path:#_ftnref17]] See the VTL 2.0 User Manual
983 +
984 +
844 844  {{putFootnotes/}}