Changes for page 4 General Notes for Implementers
Last modified by Artur on 2025/09/10 11:19
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... ... @@ -103,7 +103,7 @@ 103 103 104 104 Further to the above, the mapping between the non-native data types is presented in the table below: 105 105 106 -|**SDMX Facet**|**XML Schema**|**JSON schema **"**pattern**"[[^^~[1~]^^>>path:#_ftn1]] **for "string" type** 106 +|**SDMX Facet**|**XML Schema**|**JSON schema **"**pattern**"[[(% class="wikiinternallink" %)^^~[1~]^^>>path:#_ftn1]](%%) **for "string" type** 107 107 |GregorianYear|xsd:gYear|((( 108 108 "^-?([1-9][0-9]{3,}|0[0-9]{3})(Z|(\+|-)((0[0- 109 109 ... ... @@ -146,14 +146,11 @@ 146 146 9]+H)?([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)?$" 147 147 ))) 148 148 149 -1. 150 -11. Time and Time Format 149 +== 4.2 Time and Time Format == 151 151 152 152 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. 153 153 154 -1. 155 -11. 156 -111. Introduction 153 +=== 4.2.1 Introduction === 157 157 158 158 First, it is important to recognize that most observation times are a period. SDMX specifies precisely how Time is handled. 159 159 ... ... @@ -172,50 +172,34 @@ 172 172 173 173 The details of these time period categories and of the distinct formats which make them up are detailed in the sections to follow. 174 174 175 -1. 176 -11. 177 -111. Observational Time Period 172 +=== 4.2.2 Observational Time Period === 178 178 179 179 This is the superset of all time representations in SDMX. This allows for time to be expressed as any of the allowable formats. 180 180 181 -1. 182 -11. 183 -111. Standard Time Period 176 +=== 4.2.3 Standard Time Period === 184 184 185 185 This is the superset of any predefined time period or a distinct point in time. A time period 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). 186 186 187 -1. 188 -11. 189 -111. Gregorian Time Period 180 +=== 4.2.4 Gregorian Time Period === 190 190 191 191 A Gregorian time period is always represented by a Gregorian year, year-month, or day. These are all based on ISO 8601 dates. The representation in SDMX-ML messages and the period covered by each of the Gregorian time periods are as follows: 192 192 193 - 194 194 **Gregorian Year:** 195 195 196 196 Representation: xs:gYear (YYYY) 197 - 198 198 Period: the start of January 1 to the end of December 31 **Gregorian Year Month**: 199 - 200 200 Representation: xs:gYearMonth (YYYY-MM) 201 - 202 202 Period: the start of the first day of the month to end of the last day of the month **Gregorian Day**: 203 - 204 204 Representation: xs:date (YYYY-MM-DD) 205 - 206 206 Period: the start of the day (00:00:00) to the end of the day (23:59:59) 207 207 208 -1. 209 -11. 210 -111. Date Time 193 +=== 4.2.5 Date Time === 211 211 212 212 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 for data which is measured at a distinct point in time rather than being reported over a period, the date-time representation can be used. 213 213 214 -Representation: xs:dateTime (YYYY-MM-DDThh:mm:ss)[[^^~[2~]^^>>path:#_ftn2]] 197 +Representation: xs:dateTime (YYYY-MM-DDThh:mm:ss)[[(% class="wikiinternallink" %)^^~[2~]^^>>path:#_ftn2]] 215 215 216 -1. 217 -11. 218 -111. Standard Reporting Period 199 +=== 4.2.6 Standard Reporting Period === 219 219 220 220 Standard reporting periods are periods of time in relation to a reporting year. Each of these standard reporting periods has a duration (based on the ISO 8601 definition) associated with it. The general format of a reporting period is as follows: 221 221 ... ... @@ -224,7 +224,6 @@ 224 224 Where: 225 225 226 226 REPORTING_YEAR represents the reporting year as four digits (YYYY) PERIOD_INDICATOR identifies the type of period which determines the duration of the period 227 - 228 228 PERIOD_VALUE indicates the actual period within the year 229 229 230 230 The following section details each of the standard reporting periods defined in SDMX: ... ... @@ -283,7 +283,7 @@ 283 283 284 284 Representation: common:ReportingWeekType (YYYY-Www, e.g. 2000-W53) 285 285 286 -Notes: There are either 52 or 53 weeks in a reporting year. This is based on the ISO 8601 definition of a week (Monday - Saturday), where the first week of a reporting year is defined as the week with the first Thursday on or after the reporting year start day.[[^^~[3~]^^>>path:#_ftn3]] The reporting week is always represented as two digits, therefore 1-9 are 0 padded (e.g. 01). This allows the values to be sorted chronologically using textual sorting methods. 266 +Notes: There are either 52 or 53 weeks in a reporting year. This is based on the ISO 8601 definition of a week (Monday - Saturday), where the first week of a reporting year is defined as the week with the first Thursday on or after the reporting year start day.[[(% class="wikiinternallink" %)^^~[3~]^^>>path:#_ftn3]](%%) The reporting week is always represented as two digits, therefore 1-9 are 0 padded (e.g. 01). This allows the values to be sorted chronologically using textual sorting methods. 287 287 288 288 **Reporting Day**: 289 289 ... ... @@ -311,19 +311,19 @@ 311 311 312 312 This is the [REPORTING_YEAR_START_DATE] 313 313 314 -1. 294 +1. 315 315 11. **If the [PERIOD_INDICATOR] is W:** 316 316 111. **If [REPORTING_YEAR_START_DATE] is a Friday, Saturday, or Sunday:** 317 317 318 -Add[[^^~[4~]^^>>path:#_ftn4]] (P3D, P2D, or P1D respectively) to the [REPORTING_YEAR_START_DATE]. The result is the [REPORTING_YEAR_BASE]. 298 +Add[[(% class="wikiinternallink" %)^^~[4~]^^>>path:#_ftn4]](%%) (P3D, P2D, or P1D respectively) to the [REPORTING_YEAR_START_DATE]. The result is the [REPORTING_YEAR_BASE]. 319 319 320 -1. 321 -11. 300 +1. 301 +11. 322 322 111. **If [REPORTING_YEAR_START_DATE] is a Monday, Tuesday, Wednesday, or Thursday:** 323 323 324 324 Add^^4^^ (P0D, -P1D, -P2D, or -P3D respectively) to the [REPORTING_YEAR_START_DATE]. The result is the [REPORTING_YEAR_BASE]. 325 325 326 -1. 306 +1. 327 327 11. **Else:** 328 328 329 329 The [REPORTING_YEAR_START_DATE] is the [REPORTING_YEAR_BASE]. ... ... @@ -396,15 +396,11 @@ 396 396 397 397 The actual calendar range covered by 2011-W36 (assuming the reporting year begins July 1) is 2012-03-05T00:00:00/2012-03-11T23:59:59 398 398 399 -1. 400 -11. 401 -111. Distinct Range 379 +=== 4.2.7 Distinct Range === 402 402 403 403 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. 404 404 405 -1. 406 -11. 407 -111. Time Format 383 +=== 4.2.8 Time Format === 408 408 409 409 In version 2.0 of SDMX there is a recommendation to use the time format attribute 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 attribute in SDMX-ML. 410 410 ... ... @@ -430,11 +430,10 @@ 430 430 |RW|Reporting Week (YYYY-Www) 431 431 |RD|Reporting Day (YYYY-Dddd) 432 432 433 -==== Table 1: SDMX-ML Time Format Codes ==== 409 +(% class="wikigeneratedid" id="HTable1:SDMX-MLTimeFormatCodes" %) 410 +**Table 1: SDMX-ML Time Format Codes** 434 434 435 -1. 436 -11. 437 -111. Time Zones 412 +=== 4.2.9 Time Zones === 438 438 439 439 In alignment with ISO 8601, SDMX allows the specification of a time zone on all time periods 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. 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): 440 440 ... ... @@ -455,9 +455,7 @@ 455 455 456 456 According to ISO 8601, a date without a time-zone is considered "local time". SDMX assumes that local time is that of the sender of the message. In this version of SDMX, 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. 457 457 458 -1. 459 -11. 460 -111. Representing Time Spans Elsewhere 433 +=== 4.2.10 Representing Time Spans Elsewhere === 461 461 462 462 It has been possible since SDMX 2.0 for a Component to specify a representation of a time span. Depending on the format of the data message, this resulted in either an element with 2 XML attributes for holding the start time and the duration or two separate XML attributes based on the underlying Component identifier. For example, if REF_PERIOD were given a representation of time span, then in the Compact data format, it would be represented by two XML attributes; REF_PERIODStartTime (holding the start) and REF_PERIOD (holding the duration). If a new simple type is introduced in the SDMX schemas that can hold ISO 8601 time intervals, then this will no longer be necessary. What was represented as this: 463 463 ... ... @@ -467,21 +467,15 @@ 467 467 468 468 <Series REF_PERIOD="2000-01-01T00:00:00/P2M"/> 469 469 470 -1. 471 -11. 472 -111. Notes on Formats 443 +=== 4.2.11 Notes on Formats === 473 473 474 474 There is no ambiguity in these formats so that for any given value of time, the category of the period (and thus the intended time period 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. 475 475 476 -1. 477 -11. 478 -111. Effect on Time Ranges 447 +=== 4.2.12 Effect on Time Ranges === 479 479 480 480 All SDMX-ML data messages are capable of functioning in a manner similar to SDMXEDI if the Dimension at the observation level is time: the time period 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. 481 481 482 -1. 483 -11. 484 -111. Time in Query Messages 451 +=== 4.2.13 Time in Query Messages === 485 485 486 486 When querying for time values, the value of a time parameter can be provided as any of the Observational Time Period formats and must be paired with an operator. This section will detail how systems processing query messages should interpret these parameters. 487 487 ... ... @@ -535,9 +535,11 @@ 535 535 * 2010-M07 or later (any reporting year start day) 536 536 * 2010-W27 or later (reporting year start day ~-~-01-01)^^5^^ 537 537 * 2010-D182 or later (reporting year start day ~-~-01-01) 538 -* 2010-W28 or later (reporting year start day ~-~-07-01)^^6^^ • 2010-D185 or later (reporting year start day ~-~-07-01)539 -*1 .Versioning505 +* 2010-W28 or later (reporting year start day ~-~-07-01)^^6^^ 506 +* 2010-D185 or later (reporting year start day ~-~-07-01) 540 540 508 += 4.3 Versioning = 509 + 541 541 Versioning operates at the level of versionable and maintainable objects in the SDMX information model. Within the SDMX Structure and MetadataSet messages, there is a well-defined pattern for artefact versioning and referencing. The artefact 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". 542 542 543 543 As of SDMX 3.0, the versioning rules are extended to allow for truly versioned artefacts through the implementation of the rules of the well-known practice called "Semantic Versioning" [[(>>url:http://semver.org/]][[http:~~/~~/semver.org>>url:http://semver.org/]][[)>>url:http://semver.org/]], in addition to the legacy non-restrictive versioning scheme. In addition, the "isFinal" property is removed from ... ... @@ -546,17 +546,13 @@ 546 546 547 547 ‘1.0’. 548 548 549 -1. 550 -11. 551 -111. Non-versioned artefacts 518 +=== 4.3.1 Non-versioned artefacts === 552 552 553 553 Indeed, some use cases do not need or are incompatible with versioning for some or all their structural artefacts, such as the Agency, Data Providers, Metadata Providers and Data Consumer Schemes. These artefacts follow the legacy versioning, with a fixed version set to ‘1.0’. 554 554 555 555 Many existing organisation’s data management systems work with version-less structures and apply ad-hoc structural metadata governance processes. The new nonversioned artefacts will allow supporting those numerous situations, where organisations do not manage version numbers. 556 556 557 -1. 558 -11. 559 -111. Semantically versioned artefacts 524 +=== 4.3.2 Semantically versioned artefacts === 560 560 561 561 Since the purpose of SDMX versioning is to allow communicating the structural artefact changes to data exchange partners and connected systems, SDMX 3.0 offers Semantic Versioning (aka SemVer) with a clear and unambiguous syntax to all semantically versioned SDMX 3.0 structural artefacts. Semantic versioning will thus better respond to situations where the SDMX standard itself is the only structural contract between data providers and data consumers and where changes in structures can only be communicated through the version number increases. 562 562 ... ... @@ -580,17 +580,13 @@ 580 580 581 581 The production versions of identifiable artefacts are assumed stable, i.e., they do not have an EXTENSION. This is because once in production, an artefact cannot change in any way, or it must change the version. For cases where an artefact is not static, like during the drafting, the version must indicate this by including an EXTENSION. Draft artefacts should not be used outside of a specific system designed to accommodate them. For most purposes, all artefacts should become stable before being used in production. 582 582 583 -1. 584 -11. 585 -111. Legacy-versioned artefacts 548 +=== 4.3.3 Legacy-versioned artefacts === 586 586 587 587 Organisations wishing to keep a maximum of backwards compatibility with existing implementations can continue using the previous 2-digit convention for version numbers (MAJOR.MINOR) as in the past, such as '2.3', but without the ‘isFinal’ property. The new SDMX 3.0 standard does not add any strict rules or guarantees about changes in those artefacts, since the legacy versioning rules were rather loose and non-binding, including the meaning of the ‘isFinal’ property, and their implementations were varying. 588 588 589 589 In order to make artefacts immutable or changes truly predictable, a move to the new semantic versioning syntax is required. 590 590 591 -1. 592 -11. 593 -111. Dependency management and references 554 +=== 4.3.4 Dependency management and references === 594 594 595 595 New flexible dependency specifications with wildcarding allow for easier data model maintenance and enhancements for semantically versioned SDMX artefacts. This allows implementing a smart referencing mechanism, whereby an artefact may reference: 596 596 ... ... @@ -619,8 +619,7 @@ 619 619 620 620 Full details can be found in the SDMX RESTful web services specification. 621 621 622 -1. 623 -11. Structural Metadata Querying Best Practices 583 +== 4.4 Structural Metadata Querying Best Practices == 624 624 625 625 When querying for structural metadata, the ability to state how references should be resolved is quite powerful. However, this mechanism is not always necessary and can create an undue burden on the systems processing the queries if it is not used properly. 626 626 ... ... @@ -628,7 +628,6 @@ 628 628 629 629 When the referenced object is not known, then the reference resolution mechanism could be used. For example, suppose one wanted to find all category schemes and the related categorisations for a given maintenance agency. In this case, one could query for the category scheme by the maintenance agency and specify that parent and sibling references should be resolved. This would result in the categorisations which reference the categories in the matched schemes to be returned, as well as the object which they categorise. 630 630 631 - 632 632 ---- 633 633 634 634 [[~[1~]>>path:#_ftnref1]] Regular expressions, as specified in [[W3C XML Schema Definition Language (XSD)>>url:https://www.w3.org/TR/xmlschema11-2/]][[ >>url:https://www.w3.org/TR/xmlschema11-2/]][[1.1 Part 2: Datatypes>>url:https://www.w3.org/TR/xmlschema11-2/]][[.>>url:https://www.w3.org/TR/xmlschema11-2/]]