Wiki source code of SDMX STANDARDS

Version 14.1 by Helena on 2025/05/14 15:10

version	line-number	content
7.2	1	{{box title="Contents"}}
	2	{{toc/}}
	3	{{/box}}
	4
2.1	5	Revision History
	6
7.5	7	(% style="width:738.039px" %)
	8	\|(% style="width:187px" %)Revision\|(% style="width:157px" %)Date\|(% style="width:390px" %)Contents
	9	\|(% style="width:187px" %)DRAFT 1.0\|(% style="width:157px" %)May 2021\|(% style="width:390px" %)Draft release updated for SDMX 3.0 for public consultation
	10	\|(% style="width:187px" %)1.0\|(% style="width:157px" %)October 2021\|(% style="width:390px" %)Public Release for SDMX 3.0
2.1	11
	12	= 1 Overview =
	13
	14	SDMX version 3.0 introduces new features, improvements and changes to the Standard in the following key areas:
	15
	16	Information Model
	17
	18	* Simplification and improvement of the reference metadata model
	19	* Support for microdata
	20	* Support for geospatial data
	21	* Support for code list extension and discriminated union of code lists
	22	* Improvements to structure mapping
	23	* Improvements to code hierarchies for data discovery
	24	* Improvements to constraints
	25
	26	Versioning of Structural Metadata Artefacts
	27
7.4	28	* Adoption of the three-number semantic versioning standard for structural metadata artefacts ([[https:~~/~~/semver.org/>>https://semver.org/\|\|rel="noopener noreferrer" target="_blank"]])
2.1	29
	30	REST Web Services Application Programming Interface (API)
	31
	32	* Change to a single ‘structure’ resource for structure queries simplifying the REST API specification by reducing the number of resources to five
	33	* Improvements to data queries
	34	* Improvements to reference metadata queries
	35	* Support for structural metadata maintenance using HTTP PUT, POST and DELETE verbs
	36
	37	SOAP Web Services API
	38
7.3	39	* The SOAP web services API has been deprecated with version 3.0 standardising on REST;
2.1	40
	41	XML, JSON, CSV and EDI Transmission formats
	42
	43	* The SDMX-ML, SDMX-JSON and SDMX-CSV specifications have been extended and modified where needed to support the new features and changes such as reference metadata and microdata
	44	* Obsolete SDMX-ML data message variants including Generic, Compact, Utility and Cross-sectional have been deprecated standardising on Structure Specific Data as the sole XML format for data exchange
	45	* The SDMX-EDI transmission format for structures and data has been deprecated
	46	* The organisation of structures into ‘collections’ in SDMX-ML and SDMX-JSON structure messages has been flattened and simplified
	47	* The option to reference structures in SDMX-ML and SDMX-JSON messages using Agency, ID and Version has been deprecated with URN now exclusively used for all non-local referencing purpose
	48
	49	Breaking Changes
	50
	51	Many of the changes made are ‘breaking’ meaning that, while conversion between versions may be possible in certain circumstances, the 3.0 specification is not directly backwardly compatible with earlier versions of the Standard.
	52
	53	A summary of the main breaking changes is given in chapter 2.
	54
	55	Content of the Document
	56
	57	The remainder of the document provides a summary of the main changes. More detailed information can be found the SDMX 3.0 Technical Specifications, in particular:
	58
	59	* Section 2 – Information Model
	60	* Section 5 – Registry Specification
	61	* Section 6 – Technical Notes
	62	* SDMX-TWG GitHub for the REST API and the XML, JSON and CSV formats
	63
	64	= 2 Summary of Breaking Changes in 3.0 =
	65
	66	Version 3.0 introduces breaking changes into the web services API, transmission formats and information model. A summary is given in the table below.
	67
11.1	68	== 2.1 Web Services API ==
2.1	69
7.4	70	(% style="width:948.039px" %)
	71	\|REST API\|(% style="width:818px" %)(((
2.1	72	The REST API is not backwardly compatible due to modifications to the URLs and query parameters resulting in breaking changes in four of the five main resources:
	73
	74	* Structure queries
	75	* Data queries
	76	* Metadata queries
	77	* Availability queries
	78
	79	Schema queries are backwardly compatible.
	80
	81	//Guidance for implementors//
	82
	83	REST API implementors may provide partial backward compatibility by using web server URL rewriting rules to translate version 2.1 structure queries to the 3.0 equivalent.
	84
	85	Implementors are also recommended to version their API services providing users with an explicit choice of which version to use.
	86	)))
7.4	87	\|SOAP API\|(% style="width:818px" %)The SOAP API has been deprecated.
2.1	88
11.1	89	== 2.2 Transmission Formats ==
2.1	90
	91	(((
7.4	92	(% style="width:952.039px" %)
	93	\|(% style="width:130px" %)SDMX-ML\|(% style="width:820px" %)(((
2.1	94	The following legacy XML data messages have been deprecated:
	95
	96	SDMX-ML 1.0/2.0 Generic (time-series) data message
	97
	98	SDMX-ML 1.0/2.0 Compact (time-series) data message
	99
	100	SDMX-ML 1.0/2.0 Utility (time-series) data message
	101
	102	SDMX-ML 1.0/2.0 Cross-Sectional data message SDMX-ML 2.1 Generic data messages (for observations, time-series and cross-sectional data)
	103
	104	Structure Specific is the only data message option in version 3.0 but is not backwardly compatible with version 2.1 due to several changes including deprecation of the option to reference structures like the DSD, Dataflow and Provision Agreement using their Agency, ID and Version. The time series variant of the message has also been deprecated.
	105
	106	The SDMX-ML structure message is not backwardly compatible primarily due to:
	107
	108	* Changes to the information model
7.5	109	* Changes to the way the structures are organised into ‘collections’ within the message
2.1	110	* Deprecation of the Agency, ID, Version option for referencing of structures in messages
	111	)))
7.4	112	\|(% style="width:130px" %)SDMX-JSON\|(% style="width:820px" %)(((
2.1	113	The JSON data message is not backwardly compatible with version 2.1 primarily due to changes needed to support the improved REST API data queries, in particular the ability to retrieve in one operation data from multiple datasets with potentially different Data Structure Definitions.
	114
	115	The JSON structure message is not backwardly compatible primarily due to:
	116
	117	* Changes to the information model
7.6	118	* Changes to the way the structures are organised into ‘collections’ within the message
2.1	119	* Deprecation of the Agency, ID, Version option for referencing of structures in messages
	120	)))
7.4	121	\|(% style="width:130px" %)SDMX-EDI\|(% style="width:820px" %)The EDI format for both structures and data has been deprecated.
7.7	122	\|(% style="width:130px" %)SDMX-CSV\|(% style="width:820px" %)The CSV data and reference metadata messages are not backwardly compatible with those under version 2.1 due to changes to the structure of the messages needed to support new features such as the improved REST API data queries.
2.1	123	)))
	124
11.1	125	== 2.3 Information Model ==
2.1	126
	127	(((
7.4	128	(% style="width:955.039px" %)
	129	\|(% style="width:132px" %)Data Structure Definition\|(% style="width:819px" %)(((
2.1	130	The version 3.0 Data Structure Definition (DSD) model is not directly backwardly compatible with 2.1 primarily due to the deprecation of the special MeasureDimension.
	131
	132	//Conversion guidance for implementors//
	133
	134	Version 2.1 DSDs can be converted to the 3.0 model by creating a measure with the “MEASURE” concept role applied as described in paragraph 3.5.
	135
	136	Version 3.0 DSDs cannot be reliably converted to the 2.1 model due to the introduction of new features such as multiple measures and value arrays for measures and attributes.
	137	)))
7.4	138	\|(% style="width:132px" %)Structure mapping model\|(% style="width:819px" %)(((
2.1	139	The structure mapping model has changed significantly in version 3.0 with deprecation of the Structure Set maintainable artefact and introduction of five new ones: Representation Map and four variants of item scheme map.
	140
	141	//Conversion guidance for implementors//
	142
	143	Version 2.1 structure sets can be practically converted to the version 3.0 structure mapping model.
	144
	145	Conversion from the version 3.0 structure mapping model to 2.1 is generally possible. However, when attempting to convert mapping rules from 2.1 to 3.0 and back to 2.1, the resulting Structure Set will not be precisely the same as the original. In converting to version 3.0, the system must generate IDs for each of the new maintainable artefacts, but details of the original Structure Set artefacts are lost.
	146	)))
7.4	147	\|(% style="width:132px" %)Reference metadata model\|(% style="width:819px" %)(((
2.1	148	The reference metadata model has changed in version 3.0 with modifications to the role of the Data Structure Definition, Metadata Structure Definition and Metadataflow artefacts. Metadata Provision Agreement and Metadata Provider Scheme have been added. Metadatasets are now identifiable.
	149
	150	Version 2.1 reference metadata models are not valid in version 3.0.
	151
	152	//Conversion guidance for implementors//
	153
7.9	154	A version 2.1 Metadata Structure Definition can be converted to the version 3.0 model under some circumstances, but target information is either lost or has to be translated into a metadataflow. Further, conversion of a Data Structure Definition for collecting reference metadata against a dataset would need to make changes to the dataset’s Data Structure Definition. As the Data Structure Definition may not actually be specified, judgement would need to be taken, perhaps determining the most likely candidate by examining which already have metadata reported against their datasets. A 2.1 metadata report could be converted to a version 3.0 Metadataset if it is attached to a structure, but requires a Metadata Provision Agreement which would need to be created if not already in existence.
2.1	155
	156	Conversion from the version 3.0 model to version 2.1 cannot be performed reliably. The process would need target information to be derived from analysis of the Metadataflows and Metadata Provision Agreements. Depending on the complexity it may not be possible to express that information in a version 2.1 Data Structure Definition.
	157	)))
7.4	158	\|(% style="width:132px" %)Constraint model\|(% style="width:819px" %)(((
2.1	159	The version 2.1 Content Constraint artefact has been deprecated in version 3.0 and replaced by the Data Constraint for data, and the Metadata Constraint for reference metadata.
	160
	161	//Conversion guidance for implementors//
	162
	163	2.1 Content Constraints can be converted without loss to the equivalent version 3.0 Data Constraint model.
	164
	165	Conversion from 3.0 to 2.1 presents challenges where wildcards have been used, in those cases requiring expansion of the wildcard into explicit values.
	166	)))
7.4	167	\|(% style="width:132px" %)Hierarchical codelist structures\|(% style="width:819px" %)(((
2.1	168	The version 2.1 Hierarchical Codelist artefact has been deprecated in version 3.0 and replaced by two new artefacts, Hierarchy and Hierarchy Association.
	169
	170	//Conversion guidance for implementors//
	171
	172	Version 2.1 Hierarchical Codelists can be successfully converted to the version 3.0 hierarchy model. Information on which artefacts to link the hierarchies to on what context would need to be added as a separate procedure.
	173
	174	Conversion from the version 3.0 model to version 2.1 is possible, but with loss of the linking information
	175	)))
	176	)))
	177
	178	= 3 Information Model =
	179
11.1	180	== 3.1 Version 3.0 Information Model ==
2.1	181
	182	[[image:SDMX 3-0-0 Major Changes FINAL-1.0_en_6fc573fe.png\|\|height="404" width="718"]]
	183
	184	//Figure 1 Version 3.0 simplified Information Model UML class diagram with ‘heat map’ illustrating the areas with most change//
	185
	186	The schematic above is a simplified UML class diagram of the SDMX 3.0 information model illustrating the major areas of change as a ‘heat map’. Darker colours indicate where new structures have been added in version 3.0 or where structures have been significantly changed.
	187
	188	A number of ancillary structures including organisation schemes, process and reporting taxonomy are unchanged and have not been shown. Similarly, Organisation Scheme Map and Reporting Taxonomy Map have been omitted for simplicity. A schematic of the 2.1 model is given in Appendix A for comparison purposes.
	189
11.1	190	== 3.2 Key Changes from Version 2.1 ==
2.1	191
	192	New Maintainable Artefacts
	193
	194	* Structure Map
	195	* Representation Map
	196	* Organisation Scheme Map
	197	* Concept Scheme Map
	198	* Category Scheme Map
	199	* Reporting Taxonomy Map
	200	* Value List
	201	* Hierarchy
	202	* Hierarchy Association
	203	* Metadata Constraint
	204	* Data Constraint
	205	* Metadata Provision Agreement
	206	* Metadata Provider Scheme
	207	* Metadataset
	208
	209	New Identifiable Artefacts
	210
	211	* GeoFeatureSetCode
	212	* GeoGridCode
	213	* Metadata Provider
	214
	215	Removed Maintainable Artefacts
	216
	217	* Structure Set – replaced by Structure Map and the four item scheme maps
7.10	218	* Hierarchical Codelist – replaced by Hierarchy and Hierarchy Association
	219	* Constraint – replaced by Data Constraint and Metadata Constraint
2.1	220
	221	Changed Maintainable Artefacts
	222
	223	* Data Structure Definition – support for microdatasets and reference metadata linked to data
	224	* Metadataflow – simplifies exchange of reference metadata, in particular those linked to structures
	225	* Metadata Structure Definition – simplified model for reference metadata
	226	* Codelist – support for codelist extension and geospatial specialised codelists (GeographicCodelist, GeoGridCodelist)
	227	* VTL Mapping Scheme – VTL Concept Mapping Scheme removed to align the VTL / SDMX interface with the 3.0 model
	228
	229	New Component Representation Types
	230
	231	* GeospatialInformation – a string type where the value is an expression defining a set of geographical features using a purpose-designed syntax
	232
10.2	233	== 3.3 Areas Unchanged from Version 2.1 ==
2.1	234
	235	The following areas of the information model are unchanged from version 2.1:
	236
	237	* Categories
	238	* Concepts
	239	* Data providers
	240	* Agencies
	241	* Data consumers
	242	* VTL transformation and expressions – with the exception of VTL mapping scheme as already noted
	243	* Reporting taxonomy
	244	* Process
	245
10.2	246	== 3.4 Reference Metadata ==
2.1	247
	248	Reference metadata has been substantially re-designed for version 3.0 to simplify the model and better support practical use cases.
	249
	250	=== Simplify Metadata Structure Definition ===
	251
	252	The Metadata Structure Definition (MSD) has been simplified to remove target information, and the support of multiple report structures. The MSD now only contains Metadata Attributes which are used to define the structure of a report.
	253
	254	[[image:SDMX 3-0-0 Major Changes FINAL-1.0_en_ad5f5c97.png\|\|height="346" width="494"]]
	255
	256	//Figure 2 version 2.1 Metadata Structure Definition (MSD)//
	257
	258	[[image:SDMX 3-0-0 Major Changes FINAL-1.0_en_f2695ed5.png\|\|height="172" width="374"]]
	259
	260	//Figure 3 the simplified version 3.0 MSD//
	261
	262	=== Change to reference metadata reported against data ===
	263
	264	Reference metadata associated with datasets, data series or observations are now reported with the data. The dataset’s DSD must reference an MSD to define the structure of its reference metadata. In practice reference metadata for data are transmitted as part of the data message. The metadata attributes are treated in a similar way to the data attributes appearing in the message at the dataset, data series or individual observation level as appropriate. In contrast to simple data attributes, metadata attributes defined by an MSD can be organised into a hierarchical structure as illustrated in Figure 3 above. For this reason, metadata attributes appear in data messages structured in the same way as metadata messages.
	265
	266	The SDMX-ML example below is an excerpt from a structure specific data message illustrating reporting of reference metadata with a hierarchical structure at the observation level.
	267
	268	For completeness, the excerpt also shows:
	269
	270	* OBS_STATUS – a simple observation-level data attribute
	271	* TITLE – a multi-lingual data attribute
	272	* SOURCE_AGENCY – a multi-value data attribute
	273
13.2	274	> <Obs xsi:type="dsd:ObsType" OBS_VALUE="112" OBS_STAUS=”A” TIME_PERIOD="2010-09">
13.3	275	> <!—- complex multi-value and multi-lingual data attributes ~-~->
	276	> <Comp id="TITLE" xsi:type="ns1:TITLE_ATTRIBUTE">
	277	> <Value>
	278	> <common:Text xml:lang="en">Some English Text</common:Text>
	279	> <common:Text xml:lang="fr">Quelques textes en anglais</common:Text>
	280	> </Value>
	281	> </Comp>
	282	> <Comp id="SOURCE_AGENCY" xsi:type="ns1:SOURCE_AGENCY_ATTRIBUTE">
	283	> <Value>4F0</Value>
	284	> <Value>4D0</Value>
	285	> <Value>CZ2</Value>
	286	> </Comp>
	287	> <!—- metadata attributes are reported like in metadata messages ~-~->
13.4	288	> <Metadata>
	289	> <Attribute id="COLLECTION">
	290	> <Attribute id="METHOD">
	291	> <Text lang="en">AAA</Text>
14.1	292	> </Attribute>
13.4	293	> </Attribute>
14.1	294	> <Attribute id="CONTACT">
	295	> <Value>CONTACT 1</Value>
	296	> <Attribute id="NAME">
	297	> <Value>Contact 1 Name 1</Value>
	298	> </Attribute>
	299	> <Attribute id="NAME">
	300	> <Value>Contact 1 Name 2</Value>
	301	> </Attribute>
13.4	302	> </Attribute>
	303	> <Attribute id="CONTACT">
14.1	304	> <Value>CONTACT 2</Value>
13.4	305	> <Attribute id="NAME">
	306	> <Value>Contact 2 Name 1</Value>
14.1	307	> </Attribute>
	308	> <Attribute id="NAME">
	309	> <Value>Contact 2 Name 2</Value>
	310	> </Attribute>
	311	> </Attribute>
	312	> </Metadata>
13.3	313	> </Obs>
2.1	314
	315	=== New - Metadata Provision Agreement ===
	316
	317	In version 2.1 a Provision Agreement could be used to report information against a Dataflow or Metadataflow. From version 3.0 this is managed by two separate structures, the Data Provision Agreement and the Metadata Provision Agreement.
	318
	319	=== Move target to Metadataflow and Metadata Provision Agreement ===
	320
	321	For reference metadata that is reported against structures, the allowable targets information which is used to specify what structures the reference metadata can be reported against, has moved to the Metadataflow and can be further refined in the Metadata Provision Agreement.
	322
	323	=== Add maintainable properties to reference metadata ===
	324
	325	A Metadataset now has mandatory identification information, (owner id, id, version) enabling metadata providers to uniquely identify their reports for create, update or delete maintenance operations.
	326
10.2	327	== 3.5 Microdata Exchange ==
2.1	328
	329	Several changes have been made the Data Structure Definition to support microdata use cases in addition to aggregated time series.
	330
	331	=== Multiple measures ===
	332
	333	Multiple measures are a common characteristic of microdatasets. To support this use case, the MeasureDimension has been deprecated and replaced with the option to define zero or more measures. Measures now act like any other component in that they use concepts, can have their own local coded or uncoded representation defined within the
	334
	335	Data Structure Definition, and can be either mandatory or conditional. Creating a measure with the “MEASURE” concept role applied emulates the version 2.1
	336
	337	MeasureDimension behaviour as illustrated in the SDMX-ML example below:
	338
	339	<str:MeasureList id=”MeasureDescriptor”>
	340	<str:Measure id=”OBS_VALUE” minOccurs=”1” maxOccurs=”1” usage=”mandatory” > <str:ConceptIdentity>
	341	<Ref id=”OBS_VALUE” maintainableParentID=”CONCEPTS” agencyID=”SDMX” maintainableParentVersion=”1.0.0” />
	342	</str:ConceptIdentity>
	343	<str:LocalRepresentation>
	344	<str:TextFormat textType=”String” isMultiLingual=”true” />
	345	</str:LocalRepresentation>
	346	<str:ConceptRole>
	347	<Ref id=”MEASURE” maintainableParentID=”SDMX_CONCEPT_ROLES” agencyID=”SDMX” maintainableParentVersion=”1.0.0” />
	348	</str:ConceptRole>
	349	</str:Measure>
	350	...
	351	<str:Measure>
	352	</str:MeasureList>
	353
	354	=== Multi-value measures and attributes ===
	355
	356	Both measures and attributes have been extended with the option to take ‘arrays’ of 193 multiple coded or uncoded values. This supports use cases like multiple observation 194 status flags. New //minOccurs// and //maxOccurs// properties define the valid number of 195 values. The //usage// property separately defines whether the measure or attribute is
	357
	358	//mandatory// or optional. In the SDMX-ML measure example above, the properties
	359
	360	//minOccurs=”1” maxOccurs=”1” usage=”mandatory”// specify that OBS_VALUE must be 198 reported, and can only consist of a single value.
	361
	362	=== Attributes relationship to measures ===
	363
	364	In addition to attaching attributes to a specific level within the dataset, their relationship 202 to measures can also be defined.
	365
	366	=== Value lists ===
	367
	368	Value lists help in modelling microdata by providing an enumeration similar to code lists 206 but allowing any string values without being restricted to the rules of SDMX identifiers.
	369
	370	That allows ValueItems (the equivalent to Code) to contain symbols like ‘¥’ and ‘€’, but 208 also means they are not identifiable.
	371
10.2	372	== 3.6 Geospatial Data Exchange ==
2.1	373
	374	The version 3.0 model has been extended to provide explicit support for geospatial data.
	375
	376	=== GeospatialInformation type ===
	377
	378	A new GeospatialInformation string type has been added which can be used as the 214 representation for any dimension, attribute or measure component. The value which is a 215 string expression conforming to the syntax defined in Section 6 of the technical 216 specifications precisely defines a ‘Geo Feature Set’ – a collection of geographical 217 features like points, lines or polygons. Its use is recommended in conjunction with the “GEO_FEATURE_SET” concept role.
	379
	380	=== Geospatial code lists ===
	381
	382	Two new specialised types of code list have been added where the definition of each code includes additional geospatial information in addition to the standard ID, name and description:
	383
	384	* GeographicCodelist – each item includes an element to represent a specific Geo Feature Set which is described using the same expression syntax as for GeospatialInformation type.
	385	* GeoGridCodelist – A code list defining a geographical grid composed of cells representing regular squared portions of the Earth. Each item references a cell within the grid.
	386
11.2	387	== 3.7 Structure Mapping ==
2.1	388
	389	The Structure Set in version 2.1 is a container for many mapping structures including Data Structure Map, Codelist Map and Concept Map. For version 3.0 the Structure Set artefact has been deprecated and replaced with a number of new maintainables giving better flexibility and reusability, specifically: Structure Map, Concept Scheme Map, Representation Map, Reporting Taxonomy Map, Category Scheme Map and Organisation Scheme Map.
	390
	391	The version 2.1 Codelist Map been replaced with Representation Map which allows mappings to be defined between any combination of Code Lists, Value Lists and noncoded representations such as text strings and numbers.
	392
13.1	393	=== Many-to-many source and target components ===
2.1	394
	395	Structure mapping rules may be defined with both multiple source components and multiple target components in contrast to version 2.1 where only one source and target was allowed. That supports many-to-many (n-n) mapping use cases where the output of a mapping rule may be dependent on the combination of a number of input components. For instance:
	396
	397	Set the output component INDICATOR=”DE_A” if the input components are FREQ=”A” and REF_AREA=”DE”.
	398
	399	Similarly, an n-n rule may also set the values of any number of output components:
	400
	401	Set the output components FREQ=”A”, REF_AREA=”DE” if the input component INDICATOR=”DE_A”.
	402
	403	Fixed source and target
	404
	405	The Structure Map may now define input or output components which have a fixed value.
	406
13.1	407	=== Time representations mapping ===
2.1	408
	409	Non SDMX time representations may now be described in a Structure Map, allowing them to be mapped into SDMX time formats.
	410
13.1	411	=== Regular expression and substring mappings ===
2.1	412
	413	All item maps allow the use of regular expressions and substrings to match source values, specifically: Concept Scheme Map, Reporting Taxonomy Map, Category Scheme Map and Organisation Scheme Map.
	414
13.1	415	=== Item maps validity period ===
2.1	416
	417	Item maps may further define the period for which the mapping is valid, meaning the mapping rule will only be applied if the row of information being mapped is within the period.
	418
11.2	419	== 3.8 Constraints ==
2.1	420
	421	Constraints in version 3.0 are modelled using two separate artefacts which replace the version 2.1 content constraint:
	422
	423	* data constraint for data; and
	424	* metadata constraint for reference metadata.
	425
	426	Metadata constraint differs from its data counterpart in having a simplified cube region model better suited to reference metadata reporting use cases and not carrying details of the constrained targets – that information instead being defined directly within the metadataflow and Metadata Provision Agreement. Thus, metadata related constraints only specify constraints to the values of metadata attributes.
	427
	428	The ‘%’ wildcard character can now be used when defining cube region constraints to match multiple codes with a single expression, for instance for economic activity, ISIC4_% matches all codes beginning with ‘ISIC4_’ avoiding the need to maintain an explicit list.
	429
	430	The validity period definition has been moved from the constraint to the individual constraining terms, specifically CubeRegion, DataKeySet and MetadataTargetRegion providing more granular control.
	431
	432	Attachment constraints have been deprecated due to a lack of use cases.
	433
11.2	434	== 3.9 Code List Extension ==
2.1	435
	436	In addition to the two new specialised geospatial forms, the option has been added to define a code list as an extension of, or by inheriting codes from, other lists. An optional prefix can be added to inherited codes to disambiguate duplicates.
	437
	438	This feature allows new code lists to be easily derived from existing lists without the need to make and manually maintain copies. When querying for extended code list structures using the REST API, the option has been added to retrieve either the definition or the materialised list. Traditional literal lists of codes continue to be supported.
	439
11.2	440	== 3.10 Discriminated Union of Code Lists ==
2.1	441
	442	Combining code list extension with wildcarded constraints solves the discriminated union of code lists problem where a classification or breakdown has multiple “variants” which are all valid but mutually exclusive. A common example is economic activity where several alternative classification schemes are in use including ISIC revisions 1 to 4 and NACE as used in the European Community.
	443
11.2	444	== 3.11 Code Hierarchies ==
2.1	445
	446	Code hierarchies allow the definition of complex hierarchies of codes from potentially multiple lists for data discovery purposes. Hierarchical Codelist has been deprecated and replaced by two new artefacts: Hierarchy – the actual hierarchy of codes, and Hierarchy Association links hierarchies directly to any other identifiable object, a capability missing 312 from the version 2.1 model. Further, the linkage can be within a particular context, for instance linking a hierarchy to a dimension within the context of a specific Dataflow (dimension REF_AREA in the context of the ECB:EXR Dataflow).
	447
	448	= 4 Versioning of Structural Metadata Artefacts =
	449
7.4	450	Version 3.0 adopts semantic versioning principles for versioning of metadata artefacts following the rules set out at __[[https:~~/~~/semver.org>>https://semver.org]] __However, this is not mandatory, and organisations may continue to use the pre-existing two-digit versioning strategy, or not to version artefacts by omitting the //version// property. The version number no longer defaults to 1.0 if not explicitly set.
2.1	451
	452	Semantic version numbers are three digits:
	453
	454	MAJOR.MINOR.PATCH
	455
	456	Where
	457
	458	* The first digit (major) indicates that changes (either new features or bug fixes) are not backward compatible.
	459	* The second digit (minor) indicates that features have been added in a backward compatible manner.
	460	* The third digit (patch) indicates that bugs have been fixed in a backward compatible manner.
	461
	462	Examples:
	463
	464	SDMX:CL_AREA(1.0.0)
	465
	466	SDMX:CL_AREA(2.3.2)
	467
	468	== Dependency management ==
	469
	470	Additional constructs are possible for dependency management when referencing structures. For instance:
	471
	472	2.3+.1 Means the currently latest available version >= “2.3.1” and < “3.0.0” (all backwards compatible versions >= “2.3.1”).
	473
	474	2+.3.1 Means the currently latest available version >= “2.3.1” (even if not backwards compatible).
	475
	476	== Draft structures ==
	477
	478	A key principle is that semantically versioned structures are immutable and must not be changed without a corresponding change to the version number, except where explicitly marked as draft using extensions to the version number.
	479
	480	MAJOR.MINOR.PATCH-EXTENSION
	481
	482	1.10.0-draft Means that version 1.10.0 is still being modified and may change – equivalent to setting isFinal=false in SDMX 2.1.
	483
	484	1.10.0-unstable Alternative to -draft.
	485
	486	1.10.0-notfinal Alternative to -draft.
	487
	488	The SDMX 2.1 isFinal property is deprecated in 3.0.
	489
	490	= 5 REST Web Services API =
	491
11.1	492	== 5.1 Simplified list of resources ==
2.1	493
	494	The version 3.0 REST API has just five main resources:
	495
	496	* structure
	497	* data
	498	* schema
	499	* availability
	500	* metadata
	501
	502	All structure and item queries have been organised under the structure resource in contrast to the version 2.1 API which specified a separate resource for each structure.
	503
	504	This and changes in the URLs and query parameters on the data, availability and metadata resources means that, with the exception of schema queries, the version 3.0 API is not backwardly compatible.
	505
11.1	506	== 5.2 Improved data queries ==
2.1	507
	508	Data queries have been changed to provide more granular selections from contexts wider than just a Dataflow.
	509
	510	=== Extend the context of data retrieval ===
	511
	512	Version 2.1 data queries always retrieved data from a single specific Dataflow. In version 3.0, the query context may be specified as:
	513
	514	* Dataflow;
	515	* Data Structure Definition – i.e., all Dataflows that use it; or
	516	* Provision Agreement – i.e., all Dataflows associated with it.
	517
	518	Data queries may also search across datasets, for instance “retrieve all data about a country”.
	519
	520	=== Component-based filters ===
	521
	522	Expressions filtering on individual components can now be included as part of the data query URL.
	523
	524	/data/dataflow/ESTAT/ICP?c[REF_AREA]=CH&c[CONF_STATUS]=F
	525
	526	=== Support for operators ===
	527
	528	Filter expressions can also include operators.
	529
	530	/data/dataflow/ESTAT/ICP?c[REF_AREA]=DE&c[ICP_ITEM]=sw:01&c[TIME_PERIOD]=ge:2015 Operators include:
	531
7.4	532	(% style="width:531.039px" %)
	533	\|(% style="width:151px" %)eq\|(% style="width:378px" %)Equals
	534	\|(% style="width:151px" %)ne\|(% style="width:378px" %)Not equal to
	535	\|(% style="width:151px" %)le\|(% style="width:378px" %)Less than
	536	\|(% style="width:151px" %)ge\|(% style="width:378px" %)Greater than or equal to
	537	\|(% style="width:151px" %)sw\|(% style="width:378px" %)Starts with
2.1	538
	539	=== Support for multiple keys ===
	540
	541	Queries can now specify multiple series keys.
	542
	543	/data/dataflow/ESTAT/ICP/1.0.0/M…A.ANR,M…A.INX,M…B.CTG
	544
11.1	545	== 5.3 Improved reference metadata queries ==
2.1	546
	547	Reference metadata queries have been improved with a number of new options to retrieve metadata reports.
	548
	549	Get metadata reports by ID
	550
	551	/metadata/metadataset/ESTAT/QUALITY_REPORT/1.0.0
	552
	553	Get metadata reports by Dataflow
	554
	555	/metadata/metadataflow/ECB/METHODOLOGY/*/FR2
	556
	557	Get metadata reports about a Data Structure Definition
	558
	559	/metadata/structure/datastructure/BIS/BIS_CBS/1.0
	560
11.1	561	== 5.4 Structural metadata maintenance ==
2.1	562
	563	Support has been added for maintenance of structural metadata.
	564
	565	HTTP verbs PUT, POST and DELETE may be used to submit SDMX-ML or SDMX-JSON structure messages to an SDMX registry for the purposes of adding, updating or deleting structural metadata artefacts.
	566
	567	= 6 XML, JSON, CSV and EDI Transmission formats =
	568
11.1	569	== 6.1 SDMX-ML ==
2.1	570
	571	The SDMX-ML XML messages have been modified and updated for version 3.0. While they broadly follow the same principles, there have been significant changes which break backward compatibility.
	572
	573	=== Structure message ===
	574
	575	The SDMX-ML structure message is used for transmission of structural metadata. It closely reflects the SDMX information model and has therefore been significantly updated for version 3.0 with the addition of new structures, modifications where structures have changed, and removal of deprecated structures like Structure Set.
	576
	577	Additionally, the way the individual artefacts are organised into ‘collections’ within the message has been significantly revised with a simpler flat structure adopted as set out in the following table:
	578
7.4	579	(% style="width:1102.04px" %)
	580	\|(% style="width:321px" %)Artefact type\|(% style="width:351px" %)Version 2.1 Collection\|(% style="width:426px" %)Version 3.0 Collection
	581	\|(% style="width:321px" %)AgencyScheme\|(% style="width:351px" %)OrganisationSchemes\|(% style="width:426px" %)AgencySchemes
	582	\|(% style="width:321px" %)DataConsumerScheme\|(% style="width:351px" %)OrganisationSchemes\|(% style="width:426px" %)DataConsumerSchemes
	583	\|(% style="width:321px" %)DataProviderScheme\|(% style="width:351px" %)OrganisationSchemes\|(% style="width:426px" %)DataProviderSchemes
	584	\|(% style="width:321px" %)MetadataProviderScheme\|(% style="width:351px" %)OrganisationSchemes\|(% style="width:426px" %)MetadataProviderSchemes
	585	\|(% style="width:321px" %)OrganisationUnitScheme\|(% style="width:351px" %)OrganisationSchemes\|(% style="width:426px" %)OrganisationUnitSchemes
	586	\|(% style="width:321px" %)GeographicCodelist\|(% style="width:351px" %)Codelists\|(% style="width:426px" %)GeographicCodelists
	587	\|(% style="width:321px" %)GeoGridCodelist\|(% style="width:351px" %)Codelists\|(% style="width:426px" %)GeoGridCodelists
	588	\|(% style="width:321px" %)ConceptScheme\|(% style="width:351px" %)Concepts\|(% style="width:426px" %)ConceptSchemes
	589	\|(% style="width:321px" %)ValueList\|(% style="width:351px" %)Codelists\|(% style="width:426px" %)ValueLists
	590	\|(% style="width:321px" %)StructureMap\|(% style="width:351px" %)StructureMappings\|(% style="width:426px" %)StructureMaps
	591	\|(% style="width:321px" %)RepresentationMap\|(% style="width:351px" %)StructureMappings\|(% style="width:426px" %)RepresentationMaps
	592	\|(% style="width:321px" %)ConceptSchemeMap\|(% style="width:351px" %)StructureMappings\|(% style="width:426px" %)ConceptSchemeMaps
	593	\|(% style="width:321px" %)CategorySchemeMap\|(% style="width:351px" %)StructureMappings\|(% style="width:426px" %)CategorySchemeMaps
	594	\|(% style="width:321px" %)OrganisationSchemeMap\|(% style="width:351px" %)StructureMappings\|(% style="width:426px" %)OrganisationSchemeMaps
	595	\|(% style="width:321px" %)ReportingTaxonomyMap\|(% style="width:351px" %)StructureMappings\|(% style="width:426px" %)ReportingTaxonomyMaps
	596	\|(% style="width:321px" %)DataConstraint\|(% style="width:351px" %)Constraints\|(% style="width:426px" %)DataConstraints
	597	\|(% style="width:321px" %)MetadataConstraint\|(% style="width:351px" %)Constraints\|(% style="width:426px" %)MetadataConstraints
	598	\|(% style="width:321px" %)MetadataProvisionAgreement\|(% style="width:351px" %)ProvisionAgreement\|(% style="width:426px" %)MetadataProvisionAgreements
	599	\|(% style="width:321px" %)CustomTypeScheme\|(% style="width:351px" %)CustomTypes\|(% style="width:426px" %)CustomTypeSchemes
	600	\|(% style="width:321px" %)VtlMappingScheme\|(% style="width:351px" %)VtlMappings\|(% style="width:426px" %)VtlMappingSchemes
	601	\|(% style="width:321px" %)NamePersonalisationScheme\|(% style="width:351px" %)NamePersonalisations\|(% style="width:426px" %)NamePersonalisationSchemes
	602	\|(% style="width:321px" %)RulesetScheme\|(% style="width:351px" %)Rulesets\|(% style="width:426px" %)RulesetSchemes
	603	\|(% style="width:321px" %)TransformationScheme\|(% style="width:351px" %)Transformations\|(% style="width:426px" %)TransformationSchemes
	604	\|(% style="width:321px" %)UserDefinedOperatorScheme\|(% style="width:351px" %)UserDefinedOperators\|(% style="width:426px" %)UserDefinedOperatorSchemes
2.1	605
	606	No changes have been made to the way the following artefacts are organised in the structure message:
	607
7.4	608	(% style="width:1106.04px" %)
	609	\|(% style="width:326px" %)Artefact type\|(% style="width:776px" %)Collection
	610	\|(% style="width:326px" %)Dataflow\|(% style="width:776px" %)Dataflows
	611	\|(% style="width:326px" %)Metadataflow\|(% style="width:776px" %)Metadataflows
	612	\|(% style="width:326px" %)CategoryScheme\|(% style="width:776px" %)CategorySchemes
	613	\|(% style="width:326px" %)Categorisation\|(% style="width:776px" %)Categorisations
	614	\|(% style="width:326px" %)Codelist\|(% style="width:776px" %)Codelists
	615	\|(% style="width:326px" %)Hierarchy\|(% style="width:776px" %)Hierarchies
	616	\|(% style="width:326px" %)HierarchyAssociation\|(% style="width:776px" %)HierarchyAssociations
	617	\|(% style="width:326px" %)MetadataStructure\|(% style="width:776px" %)MetadataStructures
	618	\|(% style="width:326px" %)DataStructure\|(% style="width:776px" %)DataStructures
	619	\|(% style="width:326px" %)ReportingTaxonomy\|(% style="width:776px" %)ReportingTaxonomies
	620	\|(% style="width:326px" %)Process\|(% style="width:776px" %)Processes
	621	\|(% style="width:326px" %)ProvisionAgreement\|(% style="width:776px" %)ProvisionAgreements
2.1	622
	623	From version 3.0, collections can appear in any order within a structure message.
	624
	625	=== Data messages ===
	626
	627	All legacy SDMX-ML data messages have been deprecated with the exception of Structure Specific Data which becomes the sole standard format for transmission of SDMX data in XML in version 3.0.
	628
	629	Specifically, the following data messages are not supported in version 3.0:
	630
	631	* SDMX-ML 1.0/2.0 Generic (time-series) data message
	632	* SDMX-ML 1.0/2.0 Compact (time-series) data message
	633	* SDMX-ML 1.0/2.0 Utility (time-series) data message
	634	* SDMX-ML 1.0/2.0 Cross-Sectional data message
	635	* SDMX-ML 2.1 Generic data messages (for observations, time-series and crosssectional data)
	636
	637	The Structure Specific Data message has been extended to support the transmission of microdata sets, in particular those with multiple measures and array values for measures and attributes.
	638
	639	As detailed in paragraph 3.4, the message now additionally allows data’s reference metadata to be reported as an integral part of the dataset. Like data attributes, these metadata attributes are included in the data message at the dataset, series or observation level as appropriate.
	640
	641	The time series variant of the Structure Specific Data message is no longer used.
	642
	643	=== Reference metadata message ===
	644
	645	The Generic Metadata message remains the standard format for transmission of reference metadata sets in XML but has been modified to support the revised version 3.0 reference metadata model.
	646
	647	=== Registry structural metadata ‘query’ messages ===
	648
	649	As a consequence of the deprecation of the SOAP API and standardisation on REST, the structural metadata ‘query’ messages have all been removed. In version 3.0, querying an SDMX Registry for structural metadata is performed solely using REST GET.
	650
	651	=== Structure referencing ===
	652
	653	The option to reference structures using Agency, ID and Version has been removed. From SDMX version 3.0 URN is used for all referencing purposes with the exception of local references such as where groups reference dimensions within a DSD.
	654
11.1	655	== 6.2 SDMX-JSON ==
2.1	656
	657	Like SDMX-ML, the SDMX-JSON messages have been significantly modified and updated for version 3.0. They are not backwardly compatible with version 2.1.
	658
	659	=== Structure message ===
	660
	661	The SDMX-JSON structure message closely replicates the SDMX-ML equivalent. Like that of SDMX-ML it has been updated to align it with the version 3.0 information model with addition, deletion and modification of artefacts as required. The organisation of the structure collections has also been revised as detailed in paragraph 6.1.
	662
	663	=== Data message ===
	664
	665	The SDMX-JSON data message has similarly be updated. Additional changes have been made to allow a single message to carry data from multiple datasets with potentially different Data Structure Definitions to support REST data queries of the form “retrieve all data about a country”. For this reason, the version 3.0 SDMX-JSON is not backwardly compatible with version 2.1 data messages. Support has been added for the transmission of microdata and reporting of reference metadata on data as an integral part of the dataset.
	666
	667	=== Reference metadata message ===
	668
	669	The SDMX-JSON metadata message has also been updated to support the version 3.0 reference metadata and Metadataset specifications.
	670
	671	=== Structure referencing ===
	672
	673	As for SDMX-ML, the option to reference structures using Agency, ID and Version has been removed with URN used for all non-local referencing purposes.
	674
11.1	675	== 6.3 SDMX-CSV ==
2.1	676
	677	CSV in SDMX is used transmission of data and reference metadata only.
	678
	679	=== Data message ===
	680
	681	The SDMX-CSV data message has been modified to align with the version 3.0 information model, support the enhanced REST API and ensure that data can be freely converted to and from the XML and JSON formats without loss. These changes include:
	682
	683	* An additional column identifying the type if the artefact defining the structure of the data: “dataflow”, “datastructure” or “dataprovision”; • A column for the structure artefact’s identification of the form
	684
	685	ESTAT:NA_MAIN(1.6.0) which replaces the dataflow identifier in version 2.1; and
	686
	687	* A column for the dataset action: information, append, replace or delete, which is consistent with both the the SDMX-ML and SDMX-JSON data messages.
	688
	689	=== Reference metadata message ===
	690
	691	The SDMX-CSV metadata message is new for version 3.0 and, like the SDMX-ML and SDMX-JSON equivalents, is used for the transmission reference metadata sets.
	692
11.1	693	=== 6.4 EDI deprecation ===
2.1	694
	695	The EDI format for transmission of both structures and data has been deprecated. Version 3.0 is therefore not backwardly compatible with legacy EDI messages.
	696
	697	= Appendix A – Version 2.1 Information Model =
	698
	699	[[image:SDMX 3-0-0 Major Changes FINAL-1.0_en_5f21cdf9.png\|\|height="319" width="718"]]