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1 {{box title="**Contents**"}}
2 {{toc/}}
3 {{/box}}
4
5 This section discusses a number of topics other than the exchange of data sets in SDMX formats. Supported only in SDMX-ML (and some in SDMX-JSON), these topics include the use of the reference metadata mechanism in SDMX, the use of Structure Sets and Reporting Taxonomies, the use of Processes, a discussion of time and datatyping, and the conventional mechanisms within the SDMX-ML Structure message regarding versioning and referencing.
6
7 == {{id name="_Toc291504"/}}4.1 Representations ==
8
9 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.
10
11 There are several different representations in SDMX-ML, taken from XML Schemas and common programming languages. The table below describes the various representations, which are found in SDMX-ML, and their equivalents.
12
13 (% style="width:1185.29px" %)
14 |(% style="width:250px" %)**SDMX-ML Data Type**|(% style="width:285px" %)**XML Schema Data Type**|(% style="width:271px" %)**.NET Framework Type**|(% style="width:354px" %)**Java Data Type**
15 |(% style="width:250px" %)String|(% style="width:285px" %)xsd:string|(% style="width:271px" %)System.String|(% style="width:354px" %)java.lang.String
16 |(% style="width:250px" %)Big Integer|(% style="width:285px" %)xsd:integer|(% style="width:271px" %)System.Decimal|(% style="width:354px" %)java.math.BigInteger
17 |(% style="width:250px" %)Integer|(% style="width:285px" %)xsd:int|(% style="width:271px" %)System.Int32|(% style="width:354px" %)int
18 |(% style="width:250px" %)Long|(% style="width:285px" %)xsd.long|(% style="width:271px" %)System.Int64|(% style="width:354px" %)long
19 |(% style="width:250px" %)Short|(% style="width:285px" %)xsd:short|(% style="width:271px" %)System.Int16|(% style="width:354px" %)short
20 |(% style="width:250px" %)Decimal|(% style="width:285px" %)xsd:decimal|(% style="width:271px" %)System.Decimal|(% style="width:354px" %)java.math.BigDecimal
21 |(% style="width:250px" %)Float|(% style="width:285px" %)xsd:float|(% style="width:271px" %)System.Single|(% style="width:354px" %)float
22 |(% style="width:250px" %)Double|(% style="width:285px" %)xsd:double|(% style="width:271px" %)System.Double|(% style="width:354px" %)double
23 |(% style="width:250px" %)Boolean|(% style="width:285px" %)xsd:boolean|(% style="width:271px" %)System.Boolean|(% style="width:354px" %)boolean
24 |(% style="width:250px" %)URI|(% style="width:285px" %)xsd:anyURI|(% style="width:271px" %)System.Uri|(% style="width:354px" %)Java.net.URI or java.lang.String
25 |(% style="width:250px" %)DateTime|(% style="width:285px" %)xsd:dateTime|(% style="width:271px" %)System.DateTime|(% style="width:354px" %)javax.xml.datatype.XMLG regorianCalendar
26 |(% style="width:250px" %)Time|(% style="width:285px" %)xsd:time|(% style="width:271px" %)System.DateTime|(% style="width:354px" %)javax.xml.datatype.XMLG regorianCalendar
27 |(% style="width:250px" %)GregorianYear|(% style="width:285px" %)xsd:gYear|(% style="width:271px" %)System.DateTime|(% style="width:354px" %)javax.xml.datatype.XMLG regorianCalendar
28 |(% style="width:250px" %)GregorianMonth|(% style="width:285px" %)xsd:gYearMonth|(% style="width:271px" %)System.DateTime|(% style="width:354px" %)javax.xml.datatype.XMLG regorianCalendar
29 |(% style="width:250px" %)GregorianDay|(% style="width:285px" %)xsd:date|(% style="width:271px" %)System.DateTime|(% style="width:354px" %)javax.xml.datatype.XMLG regorianCalendar
30 |(% style="width:250px" %)Day, MonthDay, Month|(% style="width:285px" %)xsd:g*|(% style="width:271px" %)System.DateTime|(% style="width:354px" %)javax.xml.datatype.XMLG regorianCalendar
31 |(% style="width:250px" %)Duration|(% style="width:285px" %)xsd:duration|(% style="width:271px" %)System.TimeSpan|(% style="width:354px" %)javax.xml.datatype.Dura tion
32
33 There are also a number of SDMX-ML data types which do not have these direct correspondences, often because they are composite representations or restrictions of a broader data type. For most of these, there are simple types which can be referenced from the SDMX schemas, for others a derived simple type will be necessary:
34
35 * AlphaNumeric (common:AlphaNumericType, string which only allows A-z and 0-9)
36 * Alpha (common:AlphaType, string which only allows A-z)
37 * Numeric (common:NumericType, string which only allows 0-9, but is not numeric so that is can having leading zeros)
38 * Count (xs:integer, a sequence with an interval of "1")
39 * InclusiveValueRange (xs:decimal with the minValue and maxValue facets supplying the bounds)
40 * ExclusiveValueRange (xs:decimal with the minValue and maxValue facets supplying the bounds)
41 * Incremental (xs:decimal with a specified interval; the interval is typically enforced outside of the XML validation)
42 * TimeRange (common:TimeRangeType, startDateTime + Duration)
43 * ObservationalTimePeriod (common:ObservationalTimePeriodType, a union of StandardTimePeriod and TimeRange).
44 * StandardTimePeriod (common:StandardTimePeriodType, a union of BasicTimePeriod and ReportingTimePeriod).
45 * BasicTimePeriod (common:BasicTimePeriodType, a union of GregorianTimePeriod and DateTime)
46 * GregorianTimePeriod (common:GregorianTimePeriodType, a union of GregorianYear, GregorianMonth, and GregorianDay)
47 * ReportingTimePeriod (common:ReportingTimePeriodType, a union of ReportingYear, ReportingSemester, ReportingTrimester, ReportingQuarter, ReportingMonth, ReportingWeek, and ReportingDay).
48 * ReportingYear (common:ReportingYearType)
49 * ReportingSemester (common:ReportingSemesterType)
50 * ReportingTrimester (common:ReportingTrimesterType)
51 * ReportingQuarter (common:ReportingQuarterType)
52 * ReportingMonth (common:ReportingMonthType)
53 * ReportingWeek (common:ReportingWeekType)
54 * ReportingDay (common:ReportingDayType)
55 * XHTML (common:StructuredText, allows for multi-lingual text content that has XHTML markup)
56 * KeyValues (common:DataKeyType)
57 * IdentifiableReference (types for each IdentifiableObject)
58 * GeospatialInformation (a geo feature set, according to the pattern in section 7.2)
59
60 Data types also have a set of facets:
61
62 * isSequence = true | false (indicates a sequentially increasing value)
63 * minLength = positive integer (# of characters/digits)
64 * maxLength = positive integer (# of characters/digits)
65 * startValue = decimal (for numeric sequence)
66 * endValue = decimal (for numeric sequence)
67 * interval = decimal (for numeric sequence)
68 * timeInterval = duration
69 * startTime = BasicTimePeriod (for time range) endTime = BasicTimePeriod (for time range)
70 * minValue = decimal (for numeric range)
71 * maxValue = decimal (for numeric range)
72 * decimal = Integer (# of digits to right of decimal point)
73 * pattern = (a regular expression, as per W3C XML Schema)
74 * isMultiLingual = boolean (for specifying text can occur in more than one language)
75
76 Note that code lists may also have textual representations assigned to them, in addition to their enumeration of codes.
77
78 === {{id name="_Toc291505"/}}4.1.1 Data Types ===
79
80 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 3.0, between such cases.
81
82 For identifiers, text fields and Codes 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.
83
84 For example, for the id type, this is the XML schema definition:
85
86 <xs:simpleType name="IDType">
87
88 <xs:restriction base="NestedIDType">
89
90 <xs:pattern value="[A-Za-z0-9_@$\-]+"/>
91
92 </xs:restriction>
93
94 </xs:simpleType>
95
96 Where the NestedIDType is also a restriction of string.
97
98 The above looks like this, in JSON schema:
99
100 "idType": {
101
102 "type": "string",
103
104 "pattern": "^[A-Za-z0-9_@$-]+$"
105
106 }
107
108 There are also cases, though, that data types cannot be mapped like above. One such case is the array data type, which was introduced in SDMX 3.0 as a new representation. In JSON schema an array is already natively foreseen, while in the XML schema, this has to be defined as a complex type, with an SDMX specific definition (i.e., specific element/attribute names for SDMX). Beyond that, the minimum and/or maximum number of items within an array is possible in both cases.
109
110 Further to the above, the mapping between the non-native data types is presented in the table below:
111
112 |**SDMX Facet**|**XML Schema**|**JSON schema **"**pattern**"^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^1^^>>path:#sdfootnote1sym||name="sdfootnote1anc"]](%%)^^ **for "string" type**
113 |GregorianYear|xsd:gYear|(((
114 "^-?([1-9][0-9]{3,}|0[0-9]{3})(Z|(\+|-)((0[0-
115
116 9]|1[0-3]):[0-5][0-9]|14:00))?$"
117 )))
118 |GregorianMonth|xsd:gYearMonth|(((
119 "^-?([1-9][0-9]{3,}|0[0-9]{3})-(0[1-9]|1[0-
120
121 2])(Z|(\+|-)((0[0-9]|1[0-3]):[0-5][0-
122
123 9]|14:00))?$"
124 )))
125
126 [[image:SDMX 3-0-0 SECTION 6 FINAL-1.0_en_59eee18f.gif||alt="Shape1" height="1" width="192"]]
127
128 |GregorianDay|xsd:date|(((
129 "^-?([1-9][0-9]{3,}|0[0-9]{3})-(0[1-9]|1[0-2])-
130
131 (0[1-9]|[12][0-9]|3[01])(Z|(\+|-)((0[0-9]|1[0-
132
133 3]):[0-5][0-9]|14:00))?$"
134 )))
135 |Day|xsd:gDay|(((
136 "^~-~--(0[1-9]|[12][0-9]|3[01])(Z|(\+|-
137
138 )((0[0-9]|1[0-3]):[0-5][0-9]|14:00))?$"
139 )))
140 |MonthDay|xsd:gMonthDay|(((
141 "^~-~-(0[1-9]|1[0-2])-(0[1-9]|[12][0-
142
143 9]|3[01])(Z|(\+|-)((0[0-9]|1[0-3]):[0-5][0-
144
145 9]|14:00))?$"
146 )))
147 |Month|xsd:Month|(((
148 "^~-~-(0[1-9]|1[0-2])(Z|(\+|-)((0[0-9]|1[0-
149
150 3]):[0-5][0-9]|14:00))?$"
151 )))
152 |Duration|xsd:duration|(((
153 "^-?P[0-9]+Y?([0-9]+M)?([0-9]+D)?(T([0-
154
155 9]+H)?([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)?$"
156 )))
157
158 == {{id name="_Toc291506"/}}4.2 Time and Time Format ==
159
160 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.
161
162 === {{id name="_Toc291507"/}}4.2.1 Introduction ===
163
164 First, it is important to recognize that most observation times are a period. SDMX specifies precisely how Time is handled.
165
166 The representation of time is broken into a hierarchical collection of representations. A data structure definition can use of any of the representations in the hierarchy as the representation of time. This allows for the time dimension of a particular data structure definition allow for only a subset of the default representation.
167
168 The hierarchy of time formats is as follows (**bold** indicates a category which is made up of multiple formats, //italic// indicates a distinct format):
169
170 * **Observational Time Period **o **Standard Time Period**
171
172 ▪ **Basic Time Period**
173
174 * **Gregorian Time Period**
175 * //Date Time//
176
177 ▪ **Reporting Time Period**
178
179 o //Time Range//
180
181 The details of these time period categories and of the distinct formats which make them up are detailed in the sections to follow.
182
183 === {{id name="_Toc291508"/}}4.2.2 Observational Time Period ===
184
185 This is the superset of all time representations in SDMX. This allows for time to be expressed as any of the allowable formats.
186
187 === {{id name="_Toc291509"/}}4.2.3 Standard Time Period ===
188
189 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).
190
191 === {{id name="_Toc291510"/}}4.2.4 Gregorian Time Period ===
192
193 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:
194
195 **Gregorian Year:**
196
197 Representation: xs:gYear (YYYY)
198
199 Period: the start of January 1 to the end of December 31 **Gregorian Year Month**:
200
201 Representation: xs:gYearMonth (YYYY-MM)
202
203 Period: the start of the first day of the month to end of the last day of the month **Gregorian Day**:
204
205 Representation: xs:date (YYYY-MM-DD)
206
207 Period: the start of the day (00:00:00) to the end of the day (23:59:59)
208
209 === {{id name="_Toc291511"/}}4.2.5 Date Time ===
210
211 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.
212
213 Representation: xs:dateTime (YYYY-MM-DDThh:mm:ss)^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^2^^>>path:#sdfootnote2sym||name="sdfootnote2anc"]](%%)^^
214
215 === {{id name="_Toc291512"/}}4.2.6 Standard Reporting Period ===
216
217 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:
218
219 [REPORTING_YEAR]-[PERIOD_INDICATOR][PERIOD_VALUE]
220
221 Where:
222
223 REPORTING_YEAR represents the reporting year as four digits (YYYY) PERIOD_INDICATOR identifies the type of period which determines the duration of the period
224
225 PERIOD_VALUE indicates the actual period within the year
226
227 The following section details each of the standard reporting periods defined in SDMX:
228
229 **Reporting Year**:
230
231 Period Indicator: A
232
233 Period Duration: P1Y (one year)
234
235 Limit per year: 1
236
237 Representation: common:ReportingYearType (YYYY-A1, e.g. 2000-A1) **Reporting Semester:**
238
239 Period Indicator: S
240
241 Period Duration: P6M (six months)
242
243 Limit per year: 2
244
245 Representation: common:ReportingSemesterType (YYYY-Ss, e.g. 2000-S2)
246
247 [[image:SDMX 3-0-0 SECTION 6 FINAL-1.0_en_59eee18f.gif||alt="Shape2" height="1" width="192"]]
248
249 **Reporting Trimester:**
250
251 Period Indicator: T
252
253 Period Duration: P4M (four months)
254
255 Limit per year: 3
256
257 Representation: common:ReportingTrimesterType (YYYY-Tt, e.g. 2000-T3) **Reporting Quarter:**
258
259 Period Indicator: Q
260
261 Period Duration: P3M (three months)
262
263 Limit per year: 4
264
265 Representation: common:ReportingQuarterType (YYYY-Qq, e.g. 2000-Q4) **Reporting Month**:
266
267 Period Indicator: M
268
269 Period Duration: P1M (one month)
270
271 Limit per year: 1
272
273 Representation: common:ReportingMonthType (YYYY-Mmm, e.g. 2000-M12)
274
275 Notes: The reporting month 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.
276
277 **Reporting Week**:
278
279 Period Indicator: W
280
281 Period Duration: P7D (seven days)
282
283 Limit per year: 53
284
285 Representation: common:ReportingWeekType (YYYY-Www, e.g. 2000-W53)
286
287 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 wikiinternallink wikiinternallink wikiinternallink" %)^^3^^>>path:#sdfootnote3sym||name="sdfootnote3anc"]](%%)^^ 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.
288
289 **Reporting Day**:
290
291 Period Indicator: D
292
293 Period Duration: P1D (one day)
294
295 Limit per year: 366
296
297 Representation: common:ReportingDayType (YYYY-Dddd, e.g. 2000-D366)
298
299 Notes: There are either 365 or 366 days in a reporting year, depending on whether the reporting year includes leap day (February 29). The reporting day is always represented as three digits, therefore 1-99 are 0 padded (e.g. 001). This allows the values to be sorted chronologically using textual sorting methods.
300
301 The meaning of a reporting year is always based on the start day of the year and requires that the reporting year is expressed as the year at the start of the period. This start day is always the same for a reporting year, and is expressed as a day and a month (e.g. July 1). Therefore, the reporting year 2000 with a start day of July 1 begins on July 1, 2000.
302
303 A specialized attribute (reporting year start day) exists for the purpose of communicating the reporting year start day. This attribute has a fixed identifier
304
305 (REPORTING_YEAR_START_DAY) and a fixed representation (xs:gMonthDay) so that it can always be easily identified and processed in a data message. Although this attribute exists in specialized sub-class, it functions the same as any other attribute outside of its identification and representation. It must takes its identity from a concept and state its relationship with other components of the data structure definition. The ability to state this relationship allows this reporting year start day attribute to exist at the appropriate levels of a data message. In the absence of this attribute, the reporting year start date is assumed to be January 1; therefore if the reporting year coincides with the calendar year, this Attribute is not necessary.
306
307 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
308
309 Gregorian calendar period covered by the reporting period can be computed as follows
310
311 (based on the standard format of [REPROTING_YEAR]-
312
313 [PERIOD_INDICATOR][PERIOD_VALUE] and the reporting year start day as [REPORTING_YEAR_START_DAY]):
314
315 1. **Determine [REPORTING_YEAR_BASE]:**
316
317 Combine [REPORTING_YEAR] of the reporting period value (YYYY) with [REPORTING_YEAR_START_DAY] (MM-DD) to get a date (YYYY-MM-DD).
318
319 This is the [REPORTING_YEAR_START_DATE]
320
321 1.
322 11. **If the [PERIOD_INDICATOR] is W:**
323 111. **If [REPORTING_YEAR_START_DATE] is a Friday, Saturday, or Sunday:**
324
325 Add^^[[(% class="wikiinternallink wikiinternallink wikiinternallink wikiinternallink" %)^^4^^>>path:#sdfootnote4sym||name="sdfootnote4anc"]](%%)^^ (P3D, P2D, or P1D respectively) to the [REPORTING_YEAR_START_DATE]. The result is the [REPORTING_YEAR_BASE].
326
327 1.
328 11.
329 111. **If [REPORTING_YEAR_START_DATE] is a Monday, Tuesday, Wednesday, or Thursday:**
330
331 Add^^4^^ (P0D, -P1D, -P2D, or -P3D respectively) to the [REPORTING_YEAR_START_DATE]. The result is the [REPORTING_YEAR_BASE].
332
333 1.
334 11. **Else:**
335
336 The [REPORTING_YEAR_START_DATE] is the [REPORTING_YEAR_BASE].
337
338 1. **Determine [PERIOD_DURATION]:**
339 11. If the [PERIOD_INDICATOR] is A, the [PERIOD_DURATION] is P1Y.
340 11. If the [PERIOD_INDICATOR] is S, the [PERIOD_DURATION] is P6M.
341 11. If the [PERIOD_INDICATOR] is T, the [PERIOD_DURATION] is P4M.
342 11. If the [PERIOD_INDICATOR] is Q, the [PERIOD_DURATION] is P3M.
343 11. If the [PERIOD_INDICATOR] is M, the [PERIOD_DURATION] is P1M.
344 11. If the [PERIOD_INDICATOR] is W, the [PERIOD_DURATION] is P7D.
345 11. If the [PERIOD_INDICATOR] is D, the [PERIOD_DURATION] is P1D.
346 1. **Determine [PERIOD_START]:**
347
348 Subtract one from the [PERIOD_VALUE] and multiply this by the [PERIOD_DURATION]. Add^^4^^ this to the [REPORTING_YEAR_BASE]. The result is the [PERIOD_START]. **4. Determine the [PERIOD_END]:**
349
350 Multiply the [PERIOD_VALUE] by the [PERIOD_DURATION]. Add^^4^^ this to the [REPORTING_YEAR_BASE] add^^4^^ -P1D. The result is the [PERIOD_END].
351
352 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).
353
354 **Examples:**
355
356 **2010-Q2, REPORTING_YEAR_START_DAY = ~-~-07-01 (July 1)**
357
358 1. [REPORTING_YEAR_START_DATE] = 2010-07-01
359
360 b) [REPORTING_YEAR_BASE] = 2010-07-01
361
362 1. [PERIOD_DURATION] = P3M
363 1. (2-1) * P3M = P3M
364
365 2010-07-01 + P3M = 2010-10-01
366
367 [PERIOD_START] = 2010-10-01
368
369 1. 2 * P3M = P6M
370
371 2010-07-01 + P6M = 2010-13-01 = 2011-01-01
372
373 2011-01-01 + -P1D = 2010-12-31
374
375 [PERIOD_END] = 2010-12-31
376
377 The actual calendar range covered by 2010-Q2 (assuming the reporting year begins July 1) is 2010-10-01T00:00:00/2010-12-31T23:59:59
378
379 **2011-W36, REPORTING_YEAR_START_DAY = ~-~-07-01 (July 1)**
380
381 1. [REPORTING_YEAR_START_DATE] = 2010-07-01
382
383 a) 2011-07-01 = Friday
384
385 2011-07-01 + P3D = 2011-07-04
386
387 [REPORTING_YEAR_BASE] = 2011-07-04
388
389 1. [PERIOD_DURATION] = P7D
390 1. (36-1) * P7D = P245D
391
392 2011-07-04 + P245D = 2012-03-05
393
394 [PERIOD_START] = 2012-03-05
395
396 1. 36 * P7D = P252D
397
398 2011-07-04 + P252D =2012-03-12
399
400 2012-03-12 + -P1D = 2012-03-11
401
402 [PERIOD_END] = 2012-03-11
403
404 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
405
406 === {{id name="_Toc291513"/}}4.2.7 Distinct Range ===
407
408 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.
409
410 === {{id name="_Toc291514"/}}4.2.8 Time Format ===
411
412 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.
413
414 |Code|Format
415 |OTP|Observational Time Period: Superset of all SDMX time formats (Gregorian Time Period, Reporting Time Period, and Time Range)
416 |STP|Standard Time Period: Superset of Gregorian and Reporting Time Periods
417 |GTP|Superset of all Gregorian Time Periods and date-time
418 |RTP|Superset of all Reporting Time Periods
419 |TR|(((
420 Time Range: Start time and duration (YYYY-MM-
421
422 DD(Thh:mm:ss)?/<duration>)
423 )))
424 |GY|Gregorian Year (YYYY)
425 |GTM|Gregorian Year Month (YYYY-MM)
426 |GD|Gregorian Day (YYYY-MM-DD)
427 |DT|Distinct Point: date-time (YYYY-MM-DDThh:mm:ss)
428 |RY|Reporting Year (YYYY-A1)
429 |RS|Reporting Semester (YYYY-Ss)
430 |RT|Reporting Trimester (YYYY-Tt)
431 |RQ|Reporting Quarter (YYYY-Qq)
432 |RM|Reporting Month (YYYY-Mmm)
433 |RW|Reporting Week (YYYY-Www)
434 |RD|Reporting Day (YYYY-Dddd)
435
436 ==== Table 1: SDMX-ML Time Format Codes ====
437
438 === {{id name="_Toc291515"/}}4.2.9 Time Zones ===
439
440 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):
441
442 * Time Range (start date): 2006-06-05**-05:00**/P5D
443 * Time Range (start date-time): 2006-06-05T00:00:00**-05:00**/P5D
444 * Gregorian Year: 2006**-05:00**
445 * Gregorian Month: 2006-06**-05:00**
446 * Gregorian Day: 2006-06-05**-05:00**
447 * Distinct Point: 2006-06-05T00:00:00**-05:00**
448 * Reporting Year: 2006-A1**-05:00**
449 * Reporting Semester: 2006-S2**-05:00**
450 * Reporting Trimester: 2006-T2**-05:00**
451 * Reporting Quarter: 2006-Q3**-05:00**
452 * Reporting Month: 2006-M06**-05:00**
453 * Reporting Week: 2006-W23**-05:00**
454 * Reporting Day: 2006-D156**-05:00**
455 * Reporting Year Start Day: ~-~-07-01**-05:00**
456
457 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.
458
459 === {{id name="_Toc291516"/}}4.2.10 Representing Time Spans Elsewhere ===
460
461 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:
462
463 <Series REF_PERIODStartTime="2000-01-01T00:00:00" REF_PERIOD="P2M"/>
464
465 can now be represented with this:
466
467 <Series REF_PERIOD="2000-01-01T00:00:00/P2M"/>
468
469 === {{id name="_Toc291517"/}}4.2.11 Notes on Formats ===
470
471 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.
472
473 === {{id name="_Toc291518"/}}4.2.12 Effect on Time Ranges ===
474
475 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.
476
477 === 4.2.13 Time in Query Messages ===
478
479 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.
480
481 Fundamental to processing a time value parameter in a query message is understanding that all time periods should be handled as a distinct range of time. Since the time parameter in the query is paired with an operator, this also effectively represents a distinct range of time. Therefore, a system processing the query must simply match the data where the time period for requested parameter is encompassed by the time period resulting from value of the query parameter. The following table details how the operators should be interpreted for any time period provided as a parameter.
482
483 |**Operator**|**Rule**
484 |Greater Than|Any data after the last moment of the period
485 |Less Than|Any data before the first moment of the period
486 |Greater Than or Equal To|Any data on or after the first moment of the period
487 |Less Than or Equal To|Any data on or before the last moment of the period
488 |Equal To|Any data which falls on or after the first moment of the period and before or on the last moment of the period
489
490 Reporting Time Periods as query parameters are handled like this: any data within the bounds of the reporting period for the year is matched, regardless of the actual start day of the reporting year. In addition, data reported against a normal calendar period is matched if it falls within the bounds of the time parameter based on a reporting year start day of January 1. When determining whether another reporting period falls within the bounds of a report period query parameter, one will have to take into account the actual time period to compare weeks and days to higher order report periods. This will be demonstrated in the examples to follow.
491
492 **Examples:**
493
494 **Gregorian Period**
495
496 Query Parameter: Greater than 2010
497
498 Literal Interpretation: Any data where the start period occurs after 2010-1231T23:59:59.
499
500 Example Matches:
501
502 * 2011 or later
503 * 2011-01 or later
504 * 2011-01-01 or later
505 * 2011-01-01/P[Any Duration] or any later start date
506 * 2011-[Any reporting period] (any reporting year start day)
507 * 2010-S2 (reporting year start day ~-~-07-01 or later)
508 * 2010-T3 (reporting year start day ~-~-07-01 or later)
509 * 2010-Q3 or later (reporting year start day ~-~-07-01 or later)
510 * 2010-M07 or later (reporting year start day ~-~-07-01 or later)
511 * 2010-W28 or later (reporting year start day ~-~-07-01 or later)
512 * 2010-D185 or later (reporting year start day ~-~-07-01 or later)
513
514 **Reporting Period**
515
516 Query Parameter: Greater than or equal to 2010-Q3
517
518 Literal Interpretation: Any data with a reporting period where the start period is on or after the start period of 2010-Q3 for the same reporting year start day, or and data where the start period is on or after 2010-07-01. Example Matches:
519
520 * 2011 or later
521 * 2010-07 or later
522 * 2010-07-01 or later
523 * 2010-07-01/P[Any Duration] or any later start date
524 * 2011-[Any reporting period] (any reporting year start day)
525 * 2010-S2 (any reporting year start day)
526 * 2010-T3 (any reporting year start day)
527 * 2010-Q3 or later (any reporting year start day)
528 * 2010-M07 or later (any reporting year start day)
529 * 2010-W27 or later (reporting year start day ~-~-01-01)^^5^^ • 2010-D182 or later (reporting year start day ~-~-01-01)
530 * 2010-W28 or later (reporting year start day ~-~-07-01)^^6^^
531 * 2010-D185 or later (reporting year start day ~-~-07-01)
532
533 == 4.3 Versioning ==
534
535 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".
536
537 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 //MaintainableArtefact//. According to the legacy versioning, any artefact defined without a version is equivalent to following the legacy versioning, thus having version ‘1.0’.
538
539 === 4.3.1 Non-versioned artefacts ===
540
541 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’.
542
543 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.
544
545 [[image:SDMX 3-0-0 SECTION 6 FINAL-1.0_en_59eee18f.gif||alt="Shape3" height="1" width="192"]]
546
547 2010-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.
548
549 2010-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.
550
551 === 4.3.2 Semantically versioned artefacts ===
552
553 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.
554
555 The semantic 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 versions are ordered.
556
557 The detailed rules for semantic versioning are listed in chapter 14 in the annex for “Semantic Versioning”. In short, they define:
558
559 Given a version number MAJOR.MINOR.PATCH (without EXTENSION), when making changes to that semantically versioned SDMX artefact, then one must increment the:
560
561 1. MAJOR version when backwards incompatible artefact changes are made,
562 1. MINOR version when artefact elements are added in a backwards compatible manner, or
563 1. PATCH version when backwards compatible artefact property changes are made.
564
565 When incrementing a version part, the right-hand side parts are 0-ed (reset to ‘0’).
566
567 Extensions can be added, changed or dropped.
568
569 iven an extended version number MAJOR.MINOR.PATCH-EXTENSION, when making changes to that versioned artefact, then one is not required to increment the version if those changes are within the allowed scope of the version increment from the previous version (if that existed); otherwise, the above version increment rules apply. EXTENSIONs can be used e.g., for drafting or a pre-release.
570
571 Semantically versioned SDMX artefacts will thus be safe to use. Specific 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 version must be created first. Furthermore, the impact of the further change is communicated using a clear version increment. The built-in version extension facility allows for eased drafting of new SDMX artefact versions.
572
573 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.
574
575 === 4.3.3 Legacy-versioned artefacts ===
576
577 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.
578
579 In order to make artefacts immutable or changes truly predictable, a move to the new semantic versioning syntax is required.
580
581 === 4.3.4 Dependency management and references ===
582
583 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:
584
585 * a fixed version of another artefact
586 * the **latest available** version of another artefact
587 * the **latest backward compatible** version of another artefact, or the **latest backward and forward** **compatible** version of another artefact.
588
589 References not representing a strict artefact dependency, such as the target artefacts defined in a MetadataProvisionAgreement allow for linking to **all currently available** versions of another artefact. Another illustrative case for such loose referencing is that of Constraints and flows. A Constraint may reference many Dataflows or Metadataflows, the addition of more references to flow objects does not version the Constraint. This is because the Constraints are not properties of the flows – they merely make references to them.
590
591 Semantically versioned artefacts must only reference other semantically versioned artefacts, which may include extended versions. Non-versioned and legacy-versioned artefacts can reference any other non-versioned or versioned (whether semantic or legacy) artefacts. The scope of wildcards in references adapts correspondingly.
592
593 The mechanism named "early binding" refers to a dependency on a stable versioned artefact – 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 at runtime.
594
595 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, it is useful to have a scheme for external referencing. This is done at the level of maintainable objects (DSDs, Codelists, Concept Schemes, etc.) In an SDMX Structure Message, whenever an "isExternalReference" attribute is set to true, then the application must resolve the address provided in the associated "uri" attribute and use the SDMX Structure Message stored at that location for the full definition of the object in question. Alternately, if a registry "urn" attribute has been provided, the registry can be used to supply the full details of the object.
596
597 The detailed rules for dependency management and references are listed in chapter 14 in the annex for “Semantic Versioning”.
598
599 In order to allow resolving the described new forms of dependencies, the SDMX 3.0 Rest API supports retrievals legacy-versioned, wildcarded and extended artefact versions:
600
601 * Artefact queries for a **specific** version (X.Y, X.Y.Z or X.Y.Z-EXT).
602 * Artefact queries for **latest available** semantic versions within the wildcard scope (X+.Y.Z, X.Y+.Z or X.Y.Z+).
603 * Queries for **non-versioned** artefacts.
604 * Artefact queries for **all available** semantic versions within the wildcard scope (*, X.* or X.Y.*), where only the first form is required for resolving wildcarded loose references.
605
606 The combination of wildcarded queries with a specific version extension is not permitted.
607
608 Full details can be found in the SDMX RESTful web services specification.
609
610 == 4.4 Structural Metadata Querying Best Practices ==
611
612 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.
613
614 Any structural metadata object which contains a reference to an object can be queried based on that reference. For example, a categorisation references both a category and the object is it categorising. As this is the case, one can query for categorisations which categorise a particular object or which categorise against a particular category or category scheme. This mechanism should be used when the referenced object is known.
615
616 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.