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Helena 3.2 1 {{box title="**Contents**"}}
2 {{toc/}}
3 {{/box}}
Helena 2.1 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
Helena 3.2 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
Helena 2.1 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
Helena 3.3 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)
Helena 3.5 57 * IdentifiableReference (types for each IdentifiableObject)
Helena 3.4 58 * GeospatialInformation (a geo feature set, according to the pattern in section 7.2)
Helena 3.5 59
60 Data types also have a set of facets:
61
Helena 3.4 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)
Helena 3.3 68 * timeInterval = duration
Helena 3.4 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)
Helena 2.1 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
Helena 3.6 86 > <xs:simpleType name="IDType">
87 > <xs:restriction base="NestedIDType">
88 > <xs:pattern value="[A-Za-z0-9_@$\-]+"/>
89 > </xs:restriction>
90 > </xs:simpleType>
Helena 2.1 91
92 Where the NestedIDType is also a restriction of string.
93
94 The above looks like this, in JSON schema:
95
Helena 3.6 96 > "idType": {
97 > "type": "string",
98 > "pattern": "^[A-Za-z0-9_@$-]+$"
99 > }
Helena 2.1 100
101 There are also cases, though, that data types cannot be mapped like above. One such case is the array data type, which was introduced in SDMX 3.0 as a new representation. In JSON schema an array is already natively foreseen, while in the XML schema, this has to be defined as a complex type, with an SDMX specific definition (i.e., specific element/attribute names for SDMX). Beyond that, the minimum and/or maximum number of items within an array is possible in both cases.
102
103 Further to the above, the mapping between the non-native data types is presented in the table below:
104
Helena 3.7 105 (% style="width:1146.29px" %)
106 |(% style="width:159px" %)**SDMX Facet**|(% style="width:179px" %)**XML Schema**|(% style="width:800px" %)**JSON schema **"**pattern**"{{footnote}}Regular expressions, as specified in W3C XML Schema Definition Language (XSD) 1.1 Part 2: Datatypes.{{/footnote}} **for "string" type**
107 |(% style="width:159px" %)GregorianYear|(% style="width:179px" %)xsd:gYear|(% style="width:800px" %)(((
Helena 3.6 108 "^-?( [1-9] [0-9] {3,}|0[0-9]{3}) (Z| (\ + | -) ((0 [0 - 9]| 1[0 - 3]):[0 - 5] [0 - 9] | 14:00))?$"
Helena 2.1 109 )))
Helena 3.7 110 |(% style="width:159px" %)GregorianMonth|(% style="width:179px" %)xsd:gYearMonth|(% style="width:800px" %)(((
Helena 3.6 111 "^-?([1-9] [0-9] {3,}|0 [0-9] {3}) - (0 [1-9]|1[ 0- 2])(Z|(\+|-)((0[0-9]|1[0-3]):[0-5] [0 - 9]|14:00))?$"
Helena 2.1 112 )))
Helena 3.7 113 |(% style="width:163px" %)GregorianDay|(% style="width:179px" %)xsd:date|(% style="width:800px" %)(((
Helena 3.6 114 "^-?([1-9][0-9]{3,}|0[0-9]{3})-(0[1-9]|1[0-2])- (0[1-9]|[12][0-9]|3[01])(Z|(\+|-)((0[0-9]|1[0- 3]):[0-5][0-9]|14:00))?$"
Helena 2.1 115 )))
Helena 3.7 116 |(% style="width:163px" %)Day|(% style="width:179px" %)xsd:gDay|(% style="width:800px" %)(((
Helena 3.6 117 "^~-~--(0[1-9]|[12][0-9]|3[01])(Z|(\+|- )((0[0-9]|1[0-3]):[0-5][0-9]|14:00))?$"
Helena 2.1 118 )))
Helena 3.7 119 |(% style="width:163px" %)MonthDay|(% style="width:179px" %)xsd:gMonthDay|(% style="width:800px" %)(((
Helena 3.6 120 "^~-~-(0[1-9]|1[0-2])-(0[1-9]|[12][0- 9]|3[01])(Z|(\+|-)((0[0-9]|1[0-3]):[0-5][0- 9]|14:00))?$"
Helena 2.1 121 )))
Helena 3.7 122 |(% style="width:163px" %)Month|(% style="width:179px" %)xsd:Month|(% style="width:800px" %)(((
Helena 3.6 123 "^~-~-(0[1-9]|1[0-2])(Z|(\+|-)((0[0-9]|1[0- 3]):[0-5][0-9]|14:00))?$"
Helena 2.1 124 )))
Helena 3.7 125 |(% style="width:163px" %)Duration|(% style="width:179px" %)xsd:duration|(% style="width:800px" %)(((
Helena 3.6 126 "^-?P[0-9]+Y?([0-9]+M)?([0-9]+D)?(T([0- 9]+H)?([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)?$"
Helena 2.1 127 )))
128
129 == {{id name="_Toc291506"/}}4.2 Time and Time Format ==
130
131 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.
132
133 === {{id name="_Toc291507"/}}4.2.1 Introduction ===
134
135 First, it is important to recognize that most observation times are a period. SDMX specifies precisely how Time is handled.
136
137 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.
138
139 The hierarchy of time formats is as follows (**bold** indicates a category which is made up of multiple formats, //italic// indicates a distinct format):
140
Helena 3.9 141 * **Observational Time Period**
142 ** **Standard Time Period**
143 *** **Basic Time Period**
144 **** **Gregorian Time Period**
145 **** //Date Time//
146 *** **Reporting Time Period**
147 ** **//Time Range//**
Helena 2.1 148
149 The details of these time period categories and of the distinct formats which make them up are detailed in the sections to follow.
150
151 === {{id name="_Toc291508"/}}4.2.2 Observational Time Period ===
152
153 This is the superset of all time representations in SDMX. This allows for time to be expressed as any of the allowable formats.
154
155 === {{id name="_Toc291509"/}}4.2.3 Standard Time Period ===
156
157 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).
158
159 === {{id name="_Toc291510"/}}4.2.4 Gregorian Time Period ===
160
161 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:
162
163 **Gregorian Year:**
164
165 Representation: xs:gYear (YYYY)
166
Helena 3.11 167 Period: the start of January 1 to the end of December 31
Helena 2.1 168
Helena 3.11 169 **Gregorian Year Month**:
170
Helena 2.1 171 Representation: xs:gYearMonth (YYYY-MM)
172
Helena 3.11 173 Period: the start of the first day of the month to end of the last day of the month
Helena 2.1 174
Helena 3.11 175 **Gregorian Day**:
176
Helena 2.1 177 Representation: xs:date (YYYY-MM-DD)
178
179 Period: the start of the day (00:00:00) to the end of the day (23:59:59)
180
181 === {{id name="_Toc291511"/}}4.2.5 Date Time ===
182
183 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.
184
Helena 3.9 185 Representation: xs:dateTime (YYYY-MM-DDThh:mm:ss){{footnote}}The seconds can be reported fractionally{{/footnote}}
Helena 2.1 186
187 === {{id name="_Toc291512"/}}4.2.6 Standard Reporting Period ===
188
189 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:
190
191 [REPORTING_YEAR]-[PERIOD_INDICATOR][PERIOD_VALUE]
192
193 Where:
194
195 REPORTING_YEAR represents the reporting year as four digits (YYYY) PERIOD_INDICATOR identifies the type of period which determines the duration of the period
196
197 PERIOD_VALUE indicates the actual period within the year
198
199 The following section details each of the standard reporting periods defined in SDMX:
200
201 **Reporting Year**:
202
203 Period Indicator: A
204
205 Period Duration: P1Y (one year)
206
207 Limit per year: 1
208
Helena 3.12 209 Representation: common:ReportingYearType (YYYY-A1, e.g. 2000-A1)
Helena 2.1 210
Helena 3.12 211 **Reporting Semester:**
212
Helena 2.1 213 Period Indicator: S
214
215 Period Duration: P6M (six months)
216
217 Limit per year: 2
218
219 Representation: common:ReportingSemesterType (YYYY-Ss, e.g. 2000-S2)
220
221 **Reporting Trimester:**
222
223 Period Indicator: T
224
225 Period Duration: P4M (four months)
226
227 Limit per year: 3
228
Helena 3.12 229 Representation: common:ReportingTrimesterType (YYYY-Tt, e.g. 2000-T3)
Helena 2.1 230
Helena 3.12 231 **Reporting Quarter:**
232
Helena 2.1 233 Period Indicator: Q
234
235 Period Duration: P3M (three months)
236
237 Limit per year: 4
238
Helena 3.12 239 Representation: common:ReportingQuarterType (YYYY-Qq, e.g. 2000-Q4)
Helena 2.1 240
Helena 3.12 241 **Reporting Month**:
242
Helena 2.1 243 Period Indicator: M
244
245 Period Duration: P1M (one month)
246
247 Limit per year: 1
248
249 Representation: common:ReportingMonthType (YYYY-Mmm, e.g. 2000-M12)
250
251 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.
252
253 **Reporting Week**:
254
255 Period Indicator: W
256
257 Period Duration: P7D (seven days)
258
259 Limit per year: 53
260
261 Representation: common:ReportingWeekType (YYYY-Www, e.g. 2000-W53)
262
Helena 4.6 263 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 wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink wikiinternallink 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.
Helena 2.1 264
265 **Reporting Day**:
266
267 Period Indicator: D
268
269 Period Duration: P1D (one day)
270
271 Limit per year: 366
272
273 Representation: common:ReportingDayType (YYYY-Dddd, e.g. 2000-D366)
274
275 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.
276
277 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.
278
279 A specialized attribute (reporting year start day) exists for the purpose of communicating the reporting year start day. This attribute has a fixed identifier
280
281 (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.
282
Helena 4.2 283 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]):
Helena 2.1 284
Helena 4.3 285 **~1. Determine [REPORTING_YEAR_BASE]:**
Helena 2.1 286
287 Combine [REPORTING_YEAR] of the reporting period value (YYYY) with [REPORTING_YEAR_START_DAY] (MM-DD) to get a date (YYYY-MM-DD).
288 This is the [REPORTING_YEAR_START_DATE]
289
Helena 4.3 290 **a) If the [PERIOD_INDICATOR] is W:**
Helena 4.4 291
Helena 4.5 292 ~1. **If [REPORTING_YEAR_START_DATE] is a Friday, Saturday, or Sunday**:
293 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].
Helena 2.1 294
Helena 4.5 295 **~ 2. If [REPORTING_YEAR_START_DATE] is a Monday, Tuesday, Wednesday, or Thursday:**
296 Add^^4^^ (P0D, -P1D, -P2D, or -P3D respectively) to the [REPORTING_YEAR_START_DATE]. The result is the [REPORTING_YEAR_BASE].
Helena 2.1 297
Helena 4.3 298 **b) Else:**
Helena 2.1 299 The [REPORTING_YEAR_START_DATE] is the [REPORTING_YEAR_BASE].
300
Helena 4.3 301 **2. Determine [PERIOD_DURATION]:**
302 a) If the [PERIOD_INDICATOR] is A, the [PERIOD_DURATION] is P1Y.
303 b) If the [PERIOD_INDICATOR] is S, the [PERIOD_DURATION] is P6M.
304 c) If the [PERIOD_INDICATOR] is T, the [PERIOD_DURATION] is P4M.
305 d) If the [PERIOD_INDICATOR] is Q, the [PERIOD_DURATION] is P3M.
306 e) If the [PERIOD_INDICATOR] is M, the [PERIOD_DURATION] is P1M.
307 f) If the [PERIOD_INDICATOR] is W, the [PERIOD_DURATION] is P7D.
308 g) If the [PERIOD_INDICATOR] is D, the [PERIOD_DURATION] is P1D.
309 **3. Determine [PERIOD_START]:**
Helena 2.1 310
Helena 3.13 311 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].
Helena 2.1 312
Helena 3.13 313 **4. Determine the [PERIOD_END]:**
314
Helena 2.1 315 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].
316
317 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).
318
319 **Examples:**
320
321 **2010-Q2, REPORTING_YEAR_START_DAY = ~-~-07-01 (July 1)**
Helena 4.5 322 ~1. [REPORTING_YEAR_START_DATE] = 2010-07-01
323 b) [REPORTING_YEAR_BASE] = 2010-07-01
324 2. [PERIOD_DURATION] = P3M
325 3. (2-1) * P3M = P3M
326 2010-07-01 + P3M = 2010-10-01
327 [PERIOD_START] = 2010-10-01
Helena 2.1 328
Helena 4.5 329 4. 2 * P3M = P6M
330 2010-07-01 + P6M = 2010-13-01 = 2011-01-01
331 2011-01-01 + -P1D = 2010-12-31
332 [PERIOD_END] = 2010-12-31
Helena 2.1 333
334 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
335
336 **2011-W36, REPORTING_YEAR_START_DAY = ~-~-07-01 (July 1)**
Helena 4.6 337 ~1. [REPORTING_YEAR_START_DATE] = 2010-07-01
338 a) 2011-07-01 = Friday
339 2011-07-01 + P3D = 2011-07-04
340 [REPORTING_YEAR_BASE] = 2011-07-04
341 2. [PERIOD_DURATION] = P7D
342 3. (36-1) * P7D = P245D
343 2011-07-04 + P245D = 2012-03-05
344 [PERIOD_START] = 2012-03-05
345 4. 36 * P7D = P252D
346 2011-07-04 + P252D =2012-03-12
347 2012-03-12 + -P1D = 2012-03-11
348 [PERIOD_END] = 2012-03-11
Helena 2.1 349
350 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
351
352 === {{id name="_Toc291513"/}}4.2.7 Distinct Range ===
353
354 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.
355
356 === {{id name="_Toc291514"/}}4.2.8 Time Format ===
357
358 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.
359
Helena 3.13 360 (% style="width:771.294px" %)
361 |Code|(% style="width:659px" %)Format
362 |OTP|(% style="width:659px" %)Observational Time Period: Superset of all SDMX time formats (Gregorian Time Period, Reporting Time Period, and Time Range)
363 |STP|(% style="width:659px" %)Standard Time Period: Superset of Gregorian and Reporting Time Periods
364 |GTP|(% style="width:659px" %)Superset of all Gregorian Time Periods and date-time
365 |RTP|(% style="width:659px" %)Superset of all Reporting Time Periods
366 |TR|(% style="width:659px" %)(((
367 Time Range: Start time and duration (YYYY-MM-DD(Thh:mm:ss)?/<duration>)
Helena 2.1 368 )))
Helena 3.13 369 |GY|(% style="width:659px" %)Gregorian Year (YYYY)
370 |GTM|(% style="width:659px" %)Gregorian Year Month (YYYY-MM)
371 |GD|(% style="width:659px" %)Gregorian Day (YYYY-MM-DD)
372 |DT|(% style="width:659px" %)Distinct Point: date-time (YYYY-MM-DDThh:mm:ss)
373 |RY|(% style="width:659px" %)Reporting Year (YYYY-A1)
374 |RS|(% style="width:659px" %)Reporting Semester (YYYY-Ss)
375 |RT|(% style="width:659px" %)Reporting Trimester (YYYY-Tt)
376 |RQ|(% style="width:659px" %)Reporting Quarter (YYYY-Qq)
377 |RM|(% style="width:659px" %)Reporting Month (YYYY-Mmm)
378 |RW|(% style="width:659px" %)Reporting Week (YYYY-Www)
379 |RD|(% style="width:659px" %)Reporting Day (YYYY-Dddd)
Helena 2.1 380
Helena 3.13 381 (% class="wikigeneratedid" id="HTable1:SDMX-MLTimeFormatCodes" %)
382 Table 1: SDMX-ML Time Format Codes
Helena 2.1 383
384 === {{id name="_Toc291515"/}}4.2.9 Time Zones ===
385
386 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):
387
388 * Time Range (start date): 2006-06-05**-05:00**/P5D
389 * Time Range (start date-time): 2006-06-05T00:00:00**-05:00**/P5D
390 * Gregorian Year: 2006**-05:00**
391 * Gregorian Month: 2006-06**-05:00**
392 * Gregorian Day: 2006-06-05**-05:00**
393 * Distinct Point: 2006-06-05T00:00:00**-05:00**
394 * Reporting Year: 2006-A1**-05:00**
395 * Reporting Semester: 2006-S2**-05:00**
396 * Reporting Trimester: 2006-T2**-05:00**
397 * Reporting Quarter: 2006-Q3**-05:00**
398 * Reporting Month: 2006-M06**-05:00**
399 * Reporting Week: 2006-W23**-05:00**
400 * Reporting Day: 2006-D156**-05:00**
401 * Reporting Year Start Day: ~-~-07-01**-05:00**
402
403 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.
404
405 === {{id name="_Toc291516"/}}4.2.10 Representing Time Spans Elsewhere ===
406
407 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:
408
409 <Series REF_PERIODStartTime="2000-01-01T00:00:00" REF_PERIOD="P2M"/>
410
411 can now be represented with this:
412
413 <Series REF_PERIOD="2000-01-01T00:00:00/P2M"/>
414
415 === {{id name="_Toc291517"/}}4.2.11 Notes on Formats ===
416
417 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.
418
419 === {{id name="_Toc291518"/}}4.2.12 Effect on Time Ranges ===
420
421 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.
422
423 === 4.2.13 Time in Query Messages ===
424
425 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.
426
427 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.
428
Helena 3.13 429 (% style="width:1020.29px" %)
430 |(% style="width:236px" %)**Operator**|(% style="width:781px" %)**Rule**
431 |(% style="width:236px" %)Greater Than|(% style="width:781px" %)Any data after the last moment of the period
432 |(% style="width:236px" %)Less Than|(% style="width:781px" %)Any data before the first moment of the period
433 |(% style="width:236px" %)Greater Than or Equal To|(% style="width:781px" %)Any data on or after the first moment of the period
434 |(% style="width:236px" %)Less Than or Equal To|(% style="width:781px" %)Any data on or before the last moment of the period
435 |(% style="width:236px" %)Equal To|(% style="width:781px" %)Any data which falls on or after the first moment of the period and before or on the last moment of the period
Helena 2.1 436
437 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.
438
439 **Examples:**
440
441 **Gregorian Period**
442
443 Query Parameter: Greater than 2010
444
445 Literal Interpretation: Any data where the start period occurs after 2010-1231T23:59:59.
446
447 Example Matches:
448
449 * 2011 or later
450 * 2011-01 or later
451 * 2011-01-01 or later
452 * 2011-01-01/P[Any Duration] or any later start date
453 * 2011-[Any reporting period] (any reporting year start day)
454 * 2010-S2 (reporting year start day ~-~-07-01 or later)
455 * 2010-T3 (reporting year start day ~-~-07-01 or later)
456 * 2010-Q3 or later (reporting year start day ~-~-07-01 or later)
457 * 2010-M07 or later (reporting year start day ~-~-07-01 or later)
458 * 2010-W28 or later (reporting year start day ~-~-07-01 or later)
459 * 2010-D185 or later (reporting year start day ~-~-07-01 or later)
460
461 **Reporting Period**
462
463 Query Parameter: Greater than or equal to 2010-Q3
464
465 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:
466
467 * 2011 or later
468 * 2010-07 or later
469 * 2010-07-01 or later
470 * 2010-07-01/P[Any Duration] or any later start date
471 * 2011-[Any reporting period] (any reporting year start day)
472 * 2010-S2 (any reporting year start day)
473 * 2010-T3 (any reporting year start day)
474 * 2010-Q3 or later (any reporting year start day)
475 * 2010-M07 or later (any reporting year start day)
476 * 2010-W27 or later (reporting year start day ~-~-01-01)^^5^^ • 2010-D182 or later (reporting year start day ~-~-01-01)
477 * 2010-W28 or later (reporting year start day ~-~-07-01)^^6^^
478 * 2010-D185 or later (reporting year start day ~-~-07-01)
479
480 == 4.3 Versioning ==
481
482 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".
483
Helena 3.13 484 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" ([[__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 defined without a version is equivalent to following the legacy versioning, thus having version ‘1.0’.
Helena 2.1 485
486 === 4.3.1 Non-versioned artefacts ===
487
488 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’.
489
490 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.
491
492 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.
493
494 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.
495
496 === 4.3.2 Semantically versioned artefacts ===
497
498 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.
499
500 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.
501
502 The detailed rules for semantic versioning are listed in chapter 14 in the annex for “Semantic Versioning”. In short, they define:
503
504 Given a version number MAJOR.MINOR.PATCH (without EXTENSION), when making changes to that semantically versioned SDMX artefact, then one must increment the:
505
506 1. MAJOR version when backwards incompatible artefact changes are made,
507 1. MINOR version when artefact elements are added in a backwards compatible manner, or
508 1. PATCH version when backwards compatible artefact property changes are made.
509
510 When incrementing a version part, the right-hand side parts are 0-ed (reset to ‘0’).
511
512 Extensions can be added, changed or dropped.
513
514 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.
515
516 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.
517
518 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.
519
520 === 4.3.3 Legacy-versioned artefacts ===
521
522 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.
523
524 In order to make artefacts immutable or changes truly predictable, a move to the new semantic versioning syntax is required.
525
526 === 4.3.4 Dependency management and references ===
527
528 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:
529
530 * a fixed version of another artefact
531 * the **latest available** version of another artefact
532 * the **latest backward compatible** version of another artefact, or the **latest backward and forward** **compatible** version of another artefact.
533
534 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.
535
536 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.
537
538 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.
539
540 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.
541
542 The detailed rules for dependency management and references are listed in chapter 14 in the annex for “Semantic Versioning”.
543
544 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:
545
546 * Artefact queries for a **specific** version (X.Y, X.Y.Z or X.Y.Z-EXT).
547 * Artefact queries for **latest available** semantic versions within the wildcard scope (X+.Y.Z, X.Y+.Z or X.Y.Z+).
548 * Queries for **non-versioned** artefacts.
549 * 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.
550
551 The combination of wildcarded queries with a specific version extension is not permitted.
552
553 Full details can be found in the SDMX RESTful web services specification.
554
555 == 4.4 Structural Metadata Querying Best Practices ==
556
557 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.
558
559 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.
560
561 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.
Helena 3.6 562
563 {{putFootnotes/}}