Changes for page 4 General Notes for Implementers

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--Methodology.SDMX 3\.0 Standards\. Section 6\. Technical notes.WebHome
++Methodology.SDMX 3\.0 Standards\. Section 6\. Technical Notes.WebHome

Author

@@ -1,1 +1,1 @@
--xwiki:XWiki.helena
++xwiki:XWiki.elenasemanticproorg

Content

@@ -4,7 +4,7 @@
  This section discusses a number of topics other than the exchange of [[data sets>>doc:Glossary.Data set.WebHome]] in [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] formats. Supported only in [[SDMX-ML>>doc:Glossary.SDMX-ML.WebHome]] (and some in [[SDMX-JSON>>doc:Glossary.SDMX-JSON.WebHome]]), these topics include the use of the [[reference metadata>>doc:Glossary.Reference metadata.WebHome]] mechanism in [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]], the use of [[Structure Sets>>doc:Glossary.Structure set.WebHome]] and [[Reporting Taxonomies>>doc:Glossary.Reporting taxonomy.WebHome]], the use of Processes, a discussion of time and datatyping, and the conventional mechanisms within the [[SDMX-ML>>doc:Glossary.SDMX-ML.WebHome]] Structure message regarding versioning and referencing.
--== {{id name="_Toc291504"/}}4.1 Representations ==
++== 4.1 Representations ==
  This section does not go into great detail on these topics but provides a useful overview of these features to assist implementors in further use of the parts of the specification which are relevant to them.
@@ -75,9 +75,9 @@
  Note that [[code lists>>doc:Glossary.Code list.WebHome]] may also have textual [[representations>>doc:Glossary.Representation.WebHome]] assigned to them, in addition to their enumeration of [[codes>>doc:Glossary.Code.WebHome]].
--=== {{id name="_Toc291505"/}}4.1.1 Data Types ===
++=== 4.1.1 Data Types ===
--XML and JSON schemas support a variety of data types that, although rich, are not (% style="color:#e74c3c" %)mapped(%%) one-to-one in all cases. This section provides an explanation of the mapping performed in [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0, between such cases.
++XML and JSON schemas support a variety of data types that, although rich, are not mapped one-to-one in all cases. This section provides an explanation of the mapping performed in [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0, between such cases.
  For identifiers, text fields and [[Codes>>doc:Glossary.Code.WebHome]] there are no restriction from either side, since a generic type (e.g., that of string) accompanied by the proper regular expression works equally well for both XML and JSON.
@@ -98,7 +98,7 @@
  >   "pattern": "^[A-Za-z0-9_@$-]+$"
  > }
--There are also cases, though, that data types cannot be (% style="color:#e74c3c" %)mapped(%%) like above. One such case is the array data type, which was introduced in [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0 as a new [[representation>>doc:Glossary.Representation.WebHome]]. In JSON schema an array is already natively foreseen, while in the XML schema, this has to be defined as a complex type, with an [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] specific definition (i.e., specific element/[[attribute>>doc:Glossary.Attribute.WebHome]] names for [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]]). Beyond that, the minimum and/or maximum number of items within an array is possible in both cases.
++There are also cases, though, that data types cannot be mapped like above. One such case is the array data type, which was introduced in [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0 as a new [[representation>>doc:Glossary.Representation.WebHome]]. In JSON schema an array is already natively foreseen, while in the XML schema, this has to be defined as a complex type, with an [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] specific definition (i.e., specific element/[[attribute>>doc:Glossary.Attribute.WebHome]] names for [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]]). Beyond that, the minimum and/or maximum number of items within an array is possible in both cases.
  Further to the above, the mapping between the non-native data types is presented in the table below:
@@ -126,11 +126,11 @@
  "^-?P[0-9]+Y?([0-9]+M)?([0-9]+D)?(T([0- 9]+H)?([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)?$"
  )))
--== {{id name="_Toc291506"/}}4.2 Time and Time Format ==
++== 4.2 Time and Time Format ==
  This section does not go into great detail on these topics but provides a useful overview of these features to assist implementors in further use of the parts of the specification which are relevant to them.
--=== {{id name="_Toc291507"/}}4.2.1 Introduction ===
++=== 4.2.1 Introduction ===
  First, it is important to recognize that most observation times are a period. [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] specifies precisely how Time is handled.
@@ -148,15 +148,15 @@
  The details of these [[time period>>doc:Glossary.Time period.WebHome]] [[categories>>doc:Glossary.Category.WebHome]] and of the distinct formats which make them up are detailed in the sections to follow.
--=== {{id name="_Toc291508"/}}4.2.2 Observational Time Period ===
++=== 4.2.2 Observational Time Period ===
  This is the superset of all time [[representations>>doc:Glossary.Representation.WebHome]] in [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]]. This allows for time to be expressed as any of the allowable formats.
--=== {{id name="_Toc291509"/}}4.2.3 Standard Time Period ===
++=== 4.2.3 Standard Time Period ===
  This is the superset of any predefined [[time period>>doc:Glossary.Time period.WebHome]] or a distinct point in time. A [[time period>>doc:Glossary.Time period.WebHome]] consists of a distinct start and end point. If the start and end of a period are expressed as date instead of a complete date time, then it is implied that the start of the period is the beginning of the start day (i.e. 00:00:00) and the end of the period is the end of the end day (i.e. 23:59:59).
--=== {{id name="_Toc291510"/}}4.2.4 Gregorian Time Period ===
++=== 4.2.4 Gregorian Time Period ===
  A Gregorian [[time period>>doc:Glossary.Time period.WebHome]] is always represented by a Gregorian year, year-month, or day. These are all based on ISO 8601 dates. The [[representation>>doc:Glossary.Representation.WebHome]] in [[SDMX-ML>>doc:Glossary.SDMX-ML.WebHome]] messages and the period covered by each of the Gregorian [[time periods>>doc:Glossary.Time period.WebHome]] are as follows:
@@ -178,7 +178,7 @@
  Period: the start of the day (00:00:00) to the end of the day (23:59:59)
--=== {{id name="_Toc291511"/}}4.2.5 Date Time ===
++=== 4.2.5 Date Time ===
  This is used to unambiguously state that a date-time represents an observation at a single point in time. Therefore, if one wants to use [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] for data which is measured at a distinct point in time rather than being reported over a period, the date-time [[representation>>doc:Glossary.Representation.WebHome]] can be used.
@@ -250,7 +250,7 @@
  A specialized [[attribute>>doc:Glossary.Attribute.WebHome]] (reporting year start day) exists for the purpose of communicating the reporting year start day. This [[attribute>>doc:Glossary.Attribute.WebHome]] has a fixed identifier
--(REPORTING_YEAR_START_DAY) and a fixed [[representation>>doc:Glossary.Representation.WebHome]] (xs:gMonthDay) so that it can always be easily identified and processed in a data message. Although this [[attribute>>doc:Glossary.Attribute.WebHome]] exists in specialized sub-class, it functions the same as any other [[attribute>>doc:Glossary.Attribute.WebHome]] outside of its identification and [[representation>>doc:Glossary.Representation.WebHome]]. It must takes its identity from a (% style="color:#e74c3c" %)concept(%%) and state its relationship with other [[components>>doc:Glossary.Component.WebHome]] of the [[data structure definition>>doc:Glossary.Data structure definition.WebHome]]. The ability to state this relationship allows this reporting year start day [[attribute>>doc:Glossary.Attribute.WebHome]] to exist at the appropriate (% style="color:#e74c3c" %)levels(%%) of a data message. In the absence of this [[attribute>>doc:Glossary.Attribute.WebHome]], the reporting year start date is assumed to be January 1; therefore if the reporting year coincides with the calendar year, this [[Attribute>>doc:Glossary.Attribute.WebHome]] is not necessary.
++(REPORTING_YEAR_START_DAY) and a fixed [[representation>>doc:Glossary.Representation.WebHome]] (xs:gMonthDay) so that it can always be easily identified and processed in a data message. Although this [[attribute>>doc:Glossary.Attribute.WebHome]] exists in specialized sub-class, it functions the same as any other [[attribute>>doc:Glossary.Attribute.WebHome]] outside of its identification and [[representation>>doc:Glossary.Representation.WebHome]]. It must takes its identity from a (% style="color:#e74c3c" %)[[concept>>doc:sdmx:Glossary.Concept.WebHome]](%%) and state its relationship with other [[components>>doc:Glossary.Component.WebHome]] of the [[data structure definition>>doc:Glossary.Data structure definition.WebHome]]. The ability to state this relationship allows this reporting year start day [[attribute>>doc:Glossary.Attribute.WebHome]] to exist at the appropriate levels of a data message. In the absence of this [[attribute>>doc:Glossary.Attribute.WebHome]], the reporting year start date is assumed to be January 1; therefore if the reporting year coincides with the calendar year, this [[Attribute>>doc:Glossary.Attribute.WebHome]] is not necessary.
  Since the duration and the reporting year start day are known for any reporting period, it is possible to relate any reporting period to a distinct calendar period. The actual Gregorian calendar period covered by the reporting period can be computed as follows (based on the standard format of [REPROTING_YEAR]-[PERIOD_INDICATOR][PERIOD_VALUE] and the reporting year start day as [REPORTING_YEAR_START_DAY]):
@@ -263,7 +263,6 @@
        ~1. **If [REPORTING_YEAR_START_DATE] is a Friday, Saturday, or Sunday**:
         Add{{footnote}}The rules for adding durations to a date time are described in the W3C XML Schema specification. See http://www.w3.org/TR/xmlschema-2/#adding-durations-to-dateTimes for further details.{{/footnote}} (P3D, P2D, or P1D respectively) to the [REPORTING_YEAR_START_DATE]. The result is the [REPORTING_YEAR_BASE].
--
  **~      2. If [REPORTING_YEAR_START_DATE] is a Monday, Tuesday, Wednesday, or Thursday:**
        Add^^4^^ (P0D, -P1D, -P2D, or -P3D respectively) to the [REPORTING_YEAR_START_DATE]. The result is the [REPORTING_YEAR_BASE].
@@ -278,12 +278,12 @@
  e) If the [PERIOD_INDICATOR] is M, the [PERIOD_DURATION] is P1M.
  f) If the [PERIOD_INDICATOR] is W, the [PERIOD_DURATION] is P7D.
  g) If the [PERIOD_INDICATOR] is D, the [PERIOD_DURATION] is P1D.
--**3. Determine [PERIOD_START]:**
++
++**3. Determine [PERIOD_START]:**
  Subtract one from the [PERIOD_VALUE] and multiply this by the [PERIOD_DURATION]. Add{{footnote}}The rules for adding durations to a date time are described in the W3C XML Schema specification. See http://www.w3.org/TR/xmlschema-2/#adding-durations-to-dateTimes for further details.{{/footnote}} this to the [REPORTING_YEAR_BASE]. The result is the [PERIOD_START].
  **4. Determine the [PERIOD_END]:**
--
  Multiply the [PERIOD_VALUE] by the [PERIOD_DURATION]. Add{{footnote}}The rules for adding durations to a date time are described in the W3C XML Schema specification. See http://www.w3.org/TR/xmlschema-2/#adding-durations-to-dateTimes for further details.{{/footnote}} this to the [REPORTING_YEAR_BASE] add{{footnote}}The rules for adding durations to a date time are described in the W3C XML Schema specification. See http://www.w3.org/TR/xmlschema-2/#adding-durations-to-dateTimes for further details.{{/footnote}} -P1D. The result is the [PERIOD_END].
  For all of these ranges, the bounds include the beginning of the [PERIOD_START] (i.e. 00:00:00) and the end of the [PERIOD_END] (i.e. 23:59:59).
@@ -321,13 +321,13 @@
  The actual calendar range covered by 2011-W36 (assuming the reporting year begins July 1) is 2012-03-05T00:00:00/2012-03-11T23:59:59
--=== {{id name="_Toc291513"/}}4.2.7 Distinct Range ===
++=== 4.2.7 Distinct Range ===
  In the case that the reporting period does not fit into one of the prescribe periods above, a distinct time range can be used. The value of these ranges is based on the ISO 8601 time interval format of start/duration. Start can be expressed as either an ISO 8601 date or a date-time, and duration is expressed as an ISO 8601 duration. However, the duration can only be positive.
--=== {{id name="_Toc291514"/}}4.2.8 Time Format ===
++=== 4.2.8 Time Format ===
--In (% style="color:#e74c3c" %)version(%%) 2.0 of [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] there is a recommendation to use the [[time format>>doc:Glossary.Time format.WebHome]] [[attribute>>doc:Glossary.Attribute.WebHome]] to gives additional information on the way time is represented in the message. Following an appraisal of its usefulness this is no longer required. However, it is still possible, if required , to include the [[time format>>doc:Glossary.Time format.WebHome]] [[attribute>>doc:Glossary.Attribute.WebHome]] in [[SDMX-ML>>doc:Glossary.SDMX-ML.WebHome]].
++In version 2.0 of [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] there is a recommendation to use the [[time format>>doc:Glossary.Time format.WebHome]] [[attribute>>doc:Glossary.Attribute.WebHome]] to gives additional information on the way time is represented in the message. Following an appraisal of its usefulness this is no longer required. However, it is still possible, if required , to include the [[time format>>doc:Glossary.Time format.WebHome]] [[attribute>>doc:Glossary.Attribute.WebHome]] in [[SDMX-ML>>doc:Glossary.SDMX-ML.WebHome]].
  (% style="width:771.294px" %)
  |**Code**|(% style="width:659px" %)**Format**
@@ -353,7 +353,7 @@
  (% class="wikigeneratedid" id="HTable1:SDMX-MLTimeFormatCodes" %)
  **Table 1: SDMX-ML Time Format Codes**
--=== {{id name="_Toc291515"/}}4.2.9 Time Zones ===
++=== 4.2.9 Time Zones ===
  In alignment with ISO 8601, [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] allows the specification of a time zone on all [[time periods>>doc:Glossary.Time period.WebHome]] and on the reporting year start day. If a time zone is provided on a reporting year start day, then the same time zone (or none) should be reported for each reporting [[time period>>doc:Glossary.Time period.WebHome]]. If the reporting year start day and the reporting period time zone differ, the time zone of the reporting period will take precedence. Examples of each format with time zones are as follows (time zone indicated in bold):
@@ -374,7 +374,7 @@
  According to ISO 8601, a date without a time-zone is considered "local time". [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] assumes that local time is that of the sender of the message. In this (% style="color:#e74c3c" %)version(%%) of [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]], an optional field is added to the sender definition in the header for specifying a time zone. This field has a default value of 'Z' (UTC). This determination of local time applies for all dates in a message.
--=== {{id name="_Toc291516"/}}4.2.10 Representing Time Spans Elsewhere ===
++=== 4.2.10 Representing Time Spans Elsewhere ===
  It has been possible since [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 2.0 for a [[Component>>doc:Glossary.Component.WebHome]] to specify a [[representation>>doc:Glossary.Representation.WebHome]] of a time span. Depending on the format of the data message, this resulted in either an element with 2 XML [[attributes>>doc:Glossary.Attribute.WebHome]] for holding the start time and the duration or two separate XML [[attributes>>doc:Glossary.Attribute.WebHome]] based on the underlying [[Component>>doc:Glossary.Component.WebHome]] identifier. For example, if REF_PERIOD were given a [[representation>>doc:Glossary.Representation.WebHome]] of time span, then in the Compact data format, it would be represented by two XML [[attributes>>doc:Glossary.Attribute.WebHome]]; REF_PERIODStartTime (holding the start) and REF_PERIOD (holding the duration). If a new simple type is introduced in the [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] schemas that can hold ISO 8601 time intervals, then this will no longer be necessary. What was represented as this:
@@ -384,13 +384,13 @@
  > <Series REF_PERIOD="2000-01-01T00:00:00/P2M"/>
--=== {{id name="_Toc291517"/}}4.2.11 Notes on Formats ===
++=== 4.2.11 Notes on Formats ===
  There is no ambiguity in these formats so that for any given value of time, the [[category>>doc:Glossary.Category.WebHome]] of the period (and thus the intended [[time period>>doc:Glossary.Time period.WebHome]] range) is always clear. It should also be noted that by utilizing the ISO 8601 format, and a format loosely based on it for the report periods, the values of time can easily be sorted chronologically without additional parsing.
--=== {{id name="_Toc291518"/}}4.2.12 Effect on Time Ranges ===
++=== 4.2.12 Effect on Time Ranges ===
--All [[SDMX-ML>>doc:Glossary.SDMX-ML.WebHome]] data messages are capable of functioning in a manner similar to SDMXEDI if the [[Dimension>>doc:Glossary.Dimension.WebHome]] at the observation (% style="color:#e74c3c" %)level(%%) is time: the [[time period>>doc:Glossary.Time period.WebHome]] for the first observation can be stated and the rest of the observations can omit the time value as it can be derived from the start time and the frequency. Since the frequency can be determined based on the actual format of the time value for everything but distinct points in time and time ranges, this makes is even simpler to process as the interval between time ranges is known directly from the time value.
++All [[SDMX-ML>>doc:Glossary.SDMX-ML.WebHome]] data messages are capable of functioning in a manner similar to SDMXEDI if the [[Dimension>>doc:Glossary.Dimension.WebHome]] at the observation level is time: the [[time period>>doc:Glossary.Time period.WebHome]] for the first observation can be stated and the rest of the observations can omit the time value as it can be derived from the start time and the frequency. Since the frequency can be determined based on the actual format of the time value for everything but distinct points in time and time ranges, this makes is even simpler to process as the interval between time ranges is known directly from the time value.
  === 4.2.13 Time in Query Messages ===
@@ -447,43 +447,42 @@
  == 4.3 Versioning ==
--Versioning operates at the (% style="color:#e74c3c" %)level(%%) of versionable and maintainable objects in the [[SDMX information model>>doc:Glossary.SDMX Information Model.WebHome]]. Within the [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] Structure and MetadataSet messages, there is a well-defined pattern for [[artefact>>doc:Glossary.Artefact.WebHome]] versioning and referencing. The [[artefact>>doc:Glossary.Artefact.WebHome]] identifiers are qualified by their (% style="color:#e74c3c" %)version(%%) numbers – that is, an object with an Agency of "A", and ID of "X" and a (% style="color:#e74c3c" %)version(%%) of "1.0.0" is a different object than one with an Agency of "A", an ID of "X", and a (% style="color:#e74c3c" %)version(%%) of "1.1.0".
++Versioning operates at the level of versionable and maintainable objects in the [[SDMX information model>>doc:Glossary.SDMX Information Model.WebHome]]. Within the [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] Structure and MetadataSet messages, there is a well-defined pattern for [[artefact>>doc:Glossary.Artefact.WebHome]] versioning and referencing. The [[artefact>>doc:Glossary.Artefact.WebHome]] identifiers are qualified by their version numbers – that is, an object with an Agency of "A", and ID of "X" and a version of "1.0.0" is a different object than one with an Agency of "A", an ID of "X", and a version of "1.1.0".
--As of [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0, the versioning rules are extended to allow for truly versioned [[artefacts>>doc:Glossary.Artefact.WebHome]] through the implementation of the rules of the well-known practice called "Semantic Versioning" ([[__http:~~/~~/semver.org__>>https://http:semver.org]]), in addition to the legacy non-restrictive versioning scheme. In addition, the "isFinal" property is removed from //MaintainableArtefact//. According to the legacy versioning, any [[artefact>>doc:Glossary.Artefact.WebHome]] defined without a (% style="color:#e74c3c" %)version(%%) is equivalent to following the legacy versioning, thus having (% style="color:#e74c3c" %)version(%%) ‘1.0’.
++As of [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0, the versioning rules are extended to allow for truly versioned [[artefacts>>doc:Glossary.Artefact.WebHome]] through the implementation of the rules of the well-known practice called "Semantic Versioning" ([[__http:~~/~~/semver.org__>>https://http:semver.org]]), in addition to the legacy non-restrictive versioning scheme. In addition, the "isFinal" property is removed from //MaintainableArtefact//. According to the legacy versioning, any [[artefact>>doc:Glossary.Artefact.WebHome]] defined without a version is equivalent to following the legacy versioning, thus having version ‘1.0’.
  === 4.3.1 Non-versioned artefacts ===
--Indeed, some use cases do not need or are incompatible with versioning for some or all their structural [[artefacts>>doc:Glossary.Artefact.WebHome]], such as the Agency, [[Data Providers>>doc:Glossary.Data provider.WebHome]], Metadata Providers and [[Data Consumer Schemes>>doc:Glossary.Data consumer scheme.WebHome]]. These [[artefacts>>doc:Glossary.Artefact.WebHome]] follow the legacy versioning, with a fixed (% style="color:#e74c3c" %)version(%%) set to ‘1.0’.
++Indeed, some use cases do not need or are incompatible with versioning for some or all their structural [[artefacts>>doc:Glossary.Artefact.WebHome]], such as the Agency, [[Data Providers>>doc:Glossary.Data provider.WebHome]], Metadata Providers and [[Data Consumer Schemes>>doc:Glossary.Data consumer scheme.WebHome]]. These [[artefacts>>doc:Glossary.Artefact.WebHome]] follow the legacy versioning, with a fixed version set to ‘1.0’.
--Many existing organisation’s data management systems work with (% style="color:#e74c3c" %)version(%%)-less structures and apply ad-hoc [[structural metadata>>doc:Glossary.Structural metadata.WebHome]] governance processes. The new nonversioned [[artefacts>>doc:Glossary.Artefact.WebHome]] will allow supporting those numerous situations, where organisations do not manage (% style="color:#e74c3c" %)version(%%) numbers.
++Many existing organisation’s data management systems work with version-less structures and apply ad-hoc [[structural metadata>>doc:Glossary.Structural metadata.WebHome]] governance processes. The new nonversioned [[artefacts>>doc:Glossary.Artefact.WebHome]] will allow supporting those numerous situations, where organisations do not manage version numbers.
 -Q3 (with a reporting year start day of 01-01) starts on 2010-07-01. This is day 4 of week 26, therefore the first week matched is week 27.
--
 -Q3 (with a reporting year start day of 07-01) starts on 2011-01-01. This is day 6 of week 27, therefore the first week matched is week 28.
  === 4.3.2 Semantically versioned artefacts ===
--Since the purpose of [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] versioning is to allow communicating the structural [[artefact>>doc:Glossary.Artefact.WebHome]] changes to data exchange partners and connected systems, [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0 offers Semantic Versioning (aka SemVer) with a clear and unambiguous syntax to all semantically versioned [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0 structural [[artefacts>>doc:Glossary.Artefact.WebHome]]. Semantic versioning will thus better respond to situations where the [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] standard itself is the only structural contract between [[data providers>>doc:Glossary.Data provider.WebHome]] and [[data consumers>>doc:Glossary.Data consumer.WebHome]] and where changes in structures can only be communicated through the (% style="color:#e74c3c" %)version(%%) number increases.
++Since the purpose of [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] versioning is to allow communicating the structural [[artefact>>doc:Glossary.Artefact.WebHome]] changes to data exchange partners and connected systems, [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0 offers Semantic Versioning (aka SemVer) with a clear and unambiguous syntax to all semantically versioned [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0 structural [[artefacts>>doc:Glossary.Artefact.WebHome]]. Semantic versioning will thus better respond to situations where the [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] standard itself is the only structural contract between [[data providers>>doc:Glossary.Data provider.WebHome]] and [[data consumers>>doc:Glossary.Data consumer.WebHome]] and where changes in structures can only be communicated through the [[version>>doc:Glossary.Version.WebHome]] number increases.
--The semantic (% style="color:#e74c3c" %)version(%%) number consists of four parts: MAJOR, MINOR, PATCH and EXTENSION, the first three parts being separated by a dot (.), the last two parts being separated by a hyphen : MAJOR.MINOR.PATCH-EXTENSION. All (% style="color:#e74c3c" %)versions(%%) are ordered.
++The semantic [[version>>doc:Glossary.Version.WebHome]] number consists of four parts: MAJOR, MINOR, PATCH and EXTENSION, the first three parts being separated by a dot (.), the last two parts being separated by a hyphen : MAJOR.MINOR.PATCH-EXTENSION. All [[versions>>doc:Glossary.Version.WebHome]] are ordered.
  The detailed rules for semantic versioning are listed in chapter 14 in the annex for “Semantic Versioning”. In short, they define:
--Given a (% style="color:#e74c3c" %)version(%%) number MAJOR.MINOR.PATCH (without EXTENSION), when making changes to that semantically versioned [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] [[artefact>>doc:Glossary.Artefact.WebHome]], then one must increment the:
++Given a [[version>>doc:Glossary.Version.WebHome]] number MAJOR.MINOR.PATCH (without EXTENSION), when making changes to that semantically versioned [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] [[artefact>>doc:Glossary.Artefact.WebHome]], then one must increment the:
--1. MAJOR (% style="color:#e74c3c" %)version(%%) when backwards incompatible [[artefact>>doc:Glossary.Artefact.WebHome]] changes are made,
--1. MINOR (% style="color:#e74c3c" %)version(%%) when [[artefact>>doc:Glossary.Artefact.WebHome]] elements are added in a backwards compatible manner, or
--1. PATCH (% style="color:#e74c3c" %)version(%%) when backwards compatible [[artefact>>doc:Glossary.Artefact.WebHome]] property changes are made.
++1. MAJOR [[version>>doc:Glossary.Version.WebHome]] when backwards incompatible [[artefact>>doc:Glossary.Artefact.WebHome]] changes are made,
++1. MINOR [[version>>doc:Glossary.Version.WebHome]] when [[artefact>>doc:Glossary.Artefact.WebHome]] elements are added in a backwards compatible manner, or
++1. PATCH [[version>>doc:Glossary.Version.WebHome]] when backwards compatible [[artefact>>doc:Glossary.Artefact.WebHome]] property changes are made.
--When incrementing a (% style="color:#e74c3c" %)version(%%) part, the right-hand side parts are 0-ed (reset to ‘0’).
++When incrementing a [[version>>doc:Glossary.Version.WebHome]] part, the right-hand side parts are 0-ed (reset to ‘0’).
  Extensions can be added, changed or dropped.
--iven an extended (% style="color:#e74c3c" %)version(%%) number MAJOR.MINOR.PATCH-EXTENSION, when making changes to that versioned [[artefact>>doc:Glossary.Artefact.WebHome]], then one is not required to increment the (% style="color:#e74c3c" %)version(%%) if those changes are within the allowed scope of the (% style="color:#e74c3c" %)version(%%) increment from the previous (% style="color:#e74c3c" %)version(%%) (if that existed); otherwise, the above (% style="color:#e74c3c" %)version(%%) increment rules apply. EXTENSIONs can be used e.g., for drafting or a pre-release.
++iven an extended [[version>>doc:Glossary.Version.WebHome]] number MAJOR.MINOR.PATCH-EXTENSION, when making changes to that versioned [[artefact>>doc:Glossary.Artefact.WebHome]], then one is not required to increment the [[version>>doc:Glossary.Version.WebHome]] if those changes are within the allowed scope of the [[version>>doc:Glossary.Version.WebHome]] increment from the previous [[version>>doc:Glossary.Version.WebHome]] (if that existed); otherwise, the above [[version>>doc:Glossary.Version.WebHome]] increment rules apply. EXTENSIONs can be used e.g., for drafting or a pre-release.
--Semantically versioned [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:Glossary.Artefact.WebHome]] will thus be safe to use. Specific (% style="color:#e74c3c" %)version(%%) patterns allow them to become either immutable, i.e., the maintainer commits to never change their content, or changeable only within a well-defined scope. If any further change is required, a new (% style="color:#e74c3c" %)version(%%) must be created first. Furthermore, the impact of the further change is communicated using a clear (% style="color:#e74c3c" %)version(%%) increment. The built-in (% style="color:#e74c3c" %)version(%%) extension facility allows for eased drafting of new [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] [[artefact>>doc:Glossary.Artefact.WebHome]] (% style="color:#e74c3c" %)versions(%%).
++Semantically versioned [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:Glossary.Artefact.WebHome]] will thus be safe to use. Specific [[version>>doc:Glossary.Version.WebHome]] patterns allow them to become either immutable, i.e., the maintainer commits to never change their content, or changeable only within a well-defined scope. If any further change is required, a new [[version>>doc:Glossary.Version.WebHome]] must be created first. Furthermore, the impact of the further change is communicated using a clear [[version>>doc:Glossary.Version.WebHome]] increment. The built-in [[version>>doc:Glossary.Version.WebHome]] extension facility allows for eased drafting of new [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] [[artefact>>doc:Glossary.Artefact.WebHome]] [[versions>>doc:Glossary.Version.WebHome]].
--The production (% style="color:#e74c3c" %)versions(%%) of [[identifiable artefacts>>doc:Glossary.Identifiable artefact.WebHome]] are assumed stable, i.e., they do not have an EXTENSION. This is because once in production, an [[artefact>>doc:Glossary.Artefact.WebHome]] cannot change in any way, or it must change the (% style="color:#e74c3c" %)version(%%). For cases where an [[artefact>>doc:Glossary.Artefact.WebHome]] is not static, like during the drafting, the (% style="color:#e74c3c" %)version(%%) must indicate this by including an EXTENSION. Draft [[artefacts>>doc:Glossary.Artefact.WebHome]] should not be used outside of a specific system designed to accommodate them. For most purposes, all [[artefacts>>doc:Glossary.Artefact.WebHome]] should become stable before being used in production.
++The production [[versions>>doc:Glossary.Version.WebHome]] of [[identifiable artefacts>>doc:Glossary.Identifiable artefact.WebHome]] are assumed stable, i.e., they do not have an EXTENSION. This is because once in production, an [[artefact>>doc:Glossary.Artefact.WebHome]] cannot change in any way, or it must change the [[version>>doc:Glossary.Version.WebHome]]. For cases where an [[artefact>>doc:Glossary.Artefact.WebHome]] is not static, like during the drafting, the [[version>>doc:Glossary.Version.WebHome]] must indicate this by including an EXTENSION. Draft [[artefacts>>doc:Glossary.Artefact.WebHome]] should not be used outside of a specific system designed to accommodate them. For most purposes, all [[artefacts>>doc:Glossary.Artefact.WebHome]] should become stable before being used in production.
  === 4.3.3 Legacy-versioned artefacts ===
@@ -495,28 +495,28 @@
  New flexible dependency specifications with wildcarding allow for easier data model maintenance and enhancements for semantically versioned [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] [[artefacts>>doc:Glossary.Artefact.WebHome]]. This allows implementing a smart referencing mechanism, whereby an [[artefact>>doc:Glossary.Artefact.WebHome]] may reference:
--* a fixed (% style="color:#e74c3c" %)version(%%) of another [[artefact>>doc:Glossary.Artefact.WebHome]]
--* the **latest available** (% style="color:#e74c3c" %)version(%%) of another [[artefact>>doc:Glossary.Artefact.WebHome]]
--* the **latest backward compatible** (% style="color:#e74c3c" %)version(%%) of another [[artefact>>doc:Glossary.Artefact.WebHome]], or the **latest backward and forward** **compatible** (% style="color:#e74c3c" %)version(%%) of another [[artefact>>doc:Glossary.Artefact.WebHome]].
++* a fixed [[version>>doc:Glossary.Version.WebHome]] of another [[artefact>>doc:Glossary.Artefact.WebHome]]
++* the **latest available** [[version>>doc:Glossary.Version.WebHome]] of another [[artefact>>doc:Glossary.Artefact.WebHome]]
++* the **latest backward compatible** [[version>>doc:Glossary.Version.WebHome]] of another [[artefact>>doc:Glossary.Artefact.WebHome]], or the **latest backward and forward** **compatible** [[version>>doc:Glossary.Version.WebHome]] of another [[artefact>>doc:Glossary.Artefact.WebHome]].
--References not representing a strict [[artefact>>doc:Glossary.Artefact.WebHome]] dependency, such as the target [[artefacts>>doc:Glossary.Artefact.WebHome]] defined in a MetadataProvisionAgreement allow for linking to **all currently available** (% style="color:#e74c3c" %)versions(%%) of another [[artefact>>doc:Glossary.Artefact.WebHome]]. Another illustrative case for such loose referencing is that of (% style="color:#e74c3c" %)Constraints(%%) and flows. A (% style="color:#e74c3c" %)Constraint(%%) may reference many [[Dataflows>>doc:Glossary.Dataflow.WebHome]] or [[Metadataflows>>doc:Glossary.Metadataflow.WebHome]], the addition of more references to flow objects does not (% style="color:#e74c3c" %)version(%%) the (% style="color:#e74c3c" %)Constraint(%%). This is because the (% style="color:#e74c3c" %)Constraints(%%) are not properties of the flows – they merely make references to them.
++References not representing a strict [[artefact>>doc:Glossary.Artefact.WebHome]] dependency, such as the target [[artefacts>>doc:Glossary.Artefact.WebHome]] defined in a MetadataProvisionAgreement allow for linking to **all currently available** [[versions>>doc:Glossary.Version.WebHome]] of another [[artefact>>doc:Glossary.Artefact.WebHome]]. Another illustrative case for such loose referencing is that of [[Constraints>>doc:Glossary.Constraint.WebHome]] and flows. A [[Constraint>>doc:Glossary.Constraint.WebHome]] may reference many [[Dataflows>>doc:Glossary.Dataflow.WebHome]] or [[Metadataflows>>doc:Glossary.Metadataflow.WebHome]], the addition of more references to flow objects does not [[version>>doc:Glossary.Version.WebHome]] the [[Constraint>>doc:Glossary.Constraint.WebHome]]. This is because the [[Constaints>>doc:Glossary.Constraint.WebHome]] are not properties of the flows – they merely make references to them.
--Semantically versioned [[artefacts>>doc:Glossary.Artefact.WebHome]] must only reference other semantically versioned [[artefacts>>doc:Glossary.Artefact.WebHome]], which may include extended (% style="color:#e74c3c" %)versions(%%). Non-versioned and legacy-versioned [[artefacts>>doc:Glossary.Artefact.WebHome]] can reference any other non-versioned or versioned (whether semantic or legacy) [[artefacts>>doc:Glossary.Artefact.WebHome]]. The scope of wildcards in references adapts correspondingly.
++Semantically versioned [[artefacts>>doc:Glossary.Artefact.WebHome]] must only reference other semantically versioned [[artefacts>>doc:Glossary.Artefact.WebHome]], which may include extended [[versions>>doc:Glossary.Version.WebHome]]. Non-versioned and legacy-versioned [[artefacts>>doc:Glossary.Artefact.WebHome]] can reference any other non-versioned or versioned (whether semantic or legacy) [[artefacts>>doc:Glossary.Artefact.WebHome]]. The scope of wildcards in references adapts correspondingly.
  The mechanism named "early binding" refers to a dependency on a stable versioned [[artefact>>doc:Glossary.Artefact.WebHome]] – everything with a stable versioned identity is a known quantity and will not change. The "late binding" mechanism is based on a wildcarded reference, and it resolves that reference and determines the currently related [[artefact>>doc:Glossary.Artefact.WebHome]] at runtime.
--One area which is much impacted by this versioning scheme is the ability to reference external objects. With the many dependencies within the various structural objects in [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]], it is useful to have a scheme for external referencing. This is done at the (% style="color:#e74c3c" %)level(%%) of maintainable objects (DSDs, Codelists, [[Concept Schemes>>doc:Glossary.Concept scheme.WebHome]], etc.) In an [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] Structure Message, whenever an [[isExternalReference>>doc:Glossary.isExternalReference.WebHome]] [[attribute>>doc:Glossary.Attribute.WebHome]] is set to true, then the application must resolve the address provided in the associated "uri" [[attribute>>doc:Glossary.Attribute.WebHome]] and use the [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] Structure Message stored at that location for the full definition of the object in question. Alternately, if a registry "urn" [[attribute>>doc:Glossary.Attribute.WebHome]] has been provided, the registry can be used to supply the full details of the object.
++One area which is much impacted by this versioning scheme is the ability to reference external objects. With the many dependencies within the various structural objects in [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]], it is useful to have a scheme for external referencing. This is done at the level of maintainable objects (DSDs, Codelists, [[Concept Schemes>>doc:Glossary.Concept scheme.WebHome]], etc.) In an [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] Structure Message, whenever an [[isExternalReference>>doc:Glossary.isExternalReference.WebHome]] [[attribute>>doc:Glossary.Attribute.WebHome]] is set to true, then the application must resolve the address provided in the associated "uri" [[attribute>>doc:Glossary.Attribute.WebHome]] and use the [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] Structure Message stored at that location for the full definition of the object in question. Alternately, if a registry "urn" [[attribute>>doc:Glossary.Attribute.WebHome]] has been provided, the registry can be used to supply the full details of the object.
  The detailed rules for dependency management and references are listed in chapter 14 in the annex for “Semantic Versioning”.
  In order to allow resolving the described new forms of dependencies, the [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] 3.0 Rest API supports retrievals legacy-versioned, wildcarded and extended [[artefact>>doc:Glossary.Artefact.WebHome]] (% style="color:#e74c3c" %)versions(%%):
--* [[Artefact>>doc:Glossary.Artefact.WebHome]] queries for a **specific** (% style="color:#e74c3c" %)version(%%) (X.Y, X.Y.Z or X.Y.Z-EXT).
--* [[Artefact>>doc:Glossary.Artefact.WebHome]] queries for **latest available** semantic (% style="color:#e74c3c" %)versions(%%) within the wildcard scope (X+.Y.Z, X.Y+.Z or X.Y.Z+).
++* [[Artefact>>doc:Glossary.Artefact.WebHome]] queries for a **specific** [[version>>doc:Glossary.Version.WebHome]] (X.Y, X.Y.Z or X.Y.Z-EXT).
++* [[Artefact>>doc:Glossary.Artefact.WebHome]] queries for **latest available** semantic [[versions>>doc:Glossary.Version.WebHome]] within the wildcard scope (X+.Y.Z, X.Y+.Z or X.Y.Z+).
  * Queries for **non-versioned** [[artefacts>>doc:Glossary.Artefact.WebHome]].
--* [[Artefact>>doc:Glossary.Artefact.WebHome]] queries for **all available** semantic (% style="color:#e74c3c" %)versions(%%) within the wildcard scope (*, X.* or X.Y.*), where only the first form is required for resolving wildcarded loose references.
++* [[Artefact>>doc:Glossary.Artefact.WebHome]] queries for **all available** semantic [[versions>>doc:Glossary.Version.WebHome]] within the wildcard scope (*, X.* or X.Y.*), where only the first form is required for resolving wildcarded loose references.
--The combination of wildcarded queries with a specific (% style="color:#e74c3c" %)version(%%) extension is not permitted.
++The combination of wildcarded queries with a specific [[version>>doc:Glossary.Version.WebHome]] extension is not permitted.
  Full details can be found in the [[SDMX>>doc:Glossary.Statistical data and metadata exchange.WebHome]] RESTful web services specification.