Syriaca.org (and the Srophé Application Framework in which it's digital publications are published) follows the ISO 8601 date and time format standards with the extra adaptations for the year zero and dates before the common era published by the W3C in XML Schema Part 2: Datatypes Second Edition). The version of ISO 8601 was that available in 2012 when the project was begun.

Following ISO 8601, dates can be entered in the eight-digit format YYYY-MM-DD. In the case of dates with reduced precision, for example where only a year is available, the date is encoded in a four-digit YYYY format. Following ISO standards, dates before the current era (BCE) are encoded in the format "-YYYY", thus 304 B.C. is encoded as "-0304". As a reminder, there is no "year zero" so any quantitative analysis using ISO date data which cross between the current era and before the current era should take this missing year into account in their calculations.

The editorial policies below also document how approximate dates, prose descriptions of date or time, and other ambiguous date and time data are encoded. The ISO publication "ISO 8601-2:2019 Date and time -- Representations for information interchange -- Part 2: Extensions" was published after these editorial policies for Syriaca.org were drafted. A future revision may attempt to align these policies with ISO 8601-2.

When editors are not able to provide a full ISO 8601 eight-digit date (for example when month or day is not known), the Syriaca.org editorial guidelines require that editors should only encode as much of the date as is known. For example encoding only the year or year and month. At the same time, some xQuery calculations in the Srophé Application Framework may still require a full eight-digit date in the YYYY-MM-DD format. For example if the application has to calculate the duration of an event it needs a precise end and start date. In these cases, the Srophé Application will add to the data a default encoding using the first day of the month in the format YYYY-01-01. These default dates are always encoded with an attribute of @syriaca-computed-start and @syriaca-computed-end so that users of the data will be aware that any dates in "syriaca-computed" attributes are only approximations created for the purpose of calculations. In every case where a "syriaca-computed" date has been added, the original less-precise but more-accurate date is also preserved in a @when attribute or similar date attribute.

<event when="0201" source="#bib78-1" syriaca-computed-start="0201-01-01" syriaca-computed-end="0201-01-01">
<p xml:lang="en">
Flood of the river
<placeName ref="http://syriaca.org/place/191">Daiṣan</placeName>
destroyed part of city.
</p>
</event>

Sources cited in the Syriac Reference Portal frequently give approximate or estimated dates in a variety of prose formats. In order to enable these approximate dates to be processed as machine-readable data, contributors should translate approximate prose dates into ranges with numeric values which reflect the level of precision in the source document.

In general the following prose conventions will be encoded into numeric values according to the following guidelines:

• Xth century -- use an 100-year range
• X-Yth centuries -- use an 100-year range for each century
• first/second half of Xth century -- use a 50-year range
• early/late Xth century -- use a 50-year range
• mid-Xth century -- use a 50-year range
• first/last quarter of Xth century -- use a 25-year range
• beginning of Xth century -- use a 25-year range at the beginning of the century plus an additional 15-year margin into the previous
• end of Xth century -- use a 25-year range at the end of the century plus an additional 15-year margin into the next

These numeric values may be combined as in the following cases:

• Early to mid Xth Century -- use a 75-year range
• late Xth century to early Yth century -- use a 100-year range across two centuries
• late Xth century to first quarter of Yth century -- use a 50-year range at the end of the century plus an additional 25-year margin into the next

NOTE: The ranges corresponding to approximate dates are not mutually exclusive (e.g. early overlaps with mid), nor should they be, since they are by nature not precise information. Accordingly, we have chosen round numbers to begin and end ranges, e.g. 0400-0450 and 0450-0500. The overlap is intended to reflect the imprecision of "first half of the fifth century" which a human author may not intend to end precisely in 0449.

For dates whose ambiguity has been emphasized by the use of “circa”, “?”, or similar wording, contributors should add additional margins of 15, 25, or 50 years to the dates (contributors may use their discretion in proportion to the size of the date ranges and the uncertainty of the date). Thus “circa Xth century” would be rendered as an 200 year range with 50-year margins on either side of the century in question. Floruit dates should be considered in this same class of highly ambiguous dates. Accordingly a floruit date of “fl. Xth century” should be rendered as an 200-year range, even though the subject is not likely to have flourished for 200 years. Given the highly ambiguous nature of dates in ancient and medieval sources, our editorial preference is to avoid creating a level of precision not supported by the sources.

These guidelines do not apply when a more precise range for a date is known (e.g. between years x and y). In such a case, these specific years should be used instead of the above ranges.

In general, approximate dates will be encoded into TEI using the @not-before and @not-after attributes (which corresponds to terminus ante/post quem). In cases where specific dates are known or where a choice of date is more appropriate than a range, the @when attribute and multiple <date> elements may be used.

Use the <origin> element (fileDesc\sourceDesc\msDesc\history\origin​) to provide the date in which a manuscript was written and, when known, the place. The element <origDate> can be used in combination with the @calendar attribute.

<history>
   <origin>
      <origDate notBefore="1600" notAfter="1700" calendar="Gregorian">xviith century</origDate>
   </origin>
</history>

Valid values for @calendar are:

1. Gregorian [=A.D.]
2. Julian
3. AM
4. Hijri-shamsi
5. Hijri-qamari [=A.H.]
6. Coptic-EoM
7. Alexandrian
8. Iranian-Yazdigird
9. Iranian-Jalali
10. Spanish
11. Ilahi
12. Hindu
13. Seleucid [=A. Gr.]
14. unknown
15. other @calendar should always be used when specific, rather than estimated, dates are mentioned.

Additionally, a number of attributes are used to qualify the <origDate> element:

1. @notBefore specifies the earliest possible date in standard form (yyyy-mm-dd)
2. @notAfter specifies the latest possible date in standard form (yyyy-mm-dd)
3. @from indicates the starting point of the period in standard form (yyyy-mm-dd)
4. @to indicates the ending point of the period in standard form (yyyy-mm-dd)
5. @when supplies the value of the date or time in a standard form (yyyy-mm-dd)

These attributes should ALWAYS contain Gregorian dates. If a non-Gregorian date is used, these attributes should be appended with "-custom" (@notBefore-custom, @notAfter-custom, @from-custom, @to-custom, @when-custom) and the element should include the @datingMethod attribute to clarify the non-Gregorian calendar:

Example for <origin>:

<origin>
     <origDate when="0615" calendar="Gregorian">A. D. 615</origDate>
     <origDate when-custom="0926" datingMethod="Seleucid">A. Gr. 926</origDate>
</origin>

All dates shouls be rendered in an ISO format and approximate dates should be converted to numeric values following the Syriaca.org Dates Guidelines: http://htmlpreview.github.io/?https://github.com/srophe/syriaca/blob/Edits-to-Date-Policy/dates.html

A. Gr. 1000 would be represented as follows:

<date notBefore=“0688-10” notAfter=“0689-09” calendar=“Gregorian”>A.D. 688/9</date>
<date when-custom=“1000” datingMethod=“Seleucid”>A. Gr. 1000</date>

And 10 June 500 A. Gr. as follows:

<date when="0188-06-10" calendar="Gregorian">June 10, 188 A.D.</date>
<date when-custom="0500-06-10" datingMethod="Seleucid-SyriacMonths">A. Gr. 500, in the month Ḥazirān, on the tenth day</date>

"Syriaca.org Dating Conventions," Syriaca.org: The Syriac Reference Portal, http://syriaca.org/documentation/wiki.html?wiki-page=/Dating-Conventions&wiki-uri=https://github.com/srophe/srophe-app-data/wiki