Cataloguing Dates

Do

• Use origDate for dates of origin in the origin section. Use date elsewhere, for example in titles, names of people, etc.
• Ensure that the contents (the text inside the tags) fully describes the date (e.g. include an indication of the calendar, such as by appending "CE" or "H"). This is what will be displayed on the web site. But it is not machine-readable, so you should also add attributes as described below, so that the date can be indexed.
• Set the calendar attribute according to how the contents expresses the date (e.g. "#Hijri-qamari" if the date is described in the Islamic lunar calendar). If the contents contains the date in two calendars, use the first, or consider splitting into two separate origDate elements.
• For attributes specifying the date, values must be in the Gregorian calendar.
• If a specific day, month or year is known, add a when attribute in the Gregorian calendar using the W3C date format (e.g. "1492", "1311-12", "1415-10-25")
• Years should be four-digits. Use zeros to pad out earlier dates. Use a minus sign for BCE dates.
• If there is a range within which the manuscript (or part) originated, use notBefore and notAfter attributes, again with values that are W3C format dates in the Gregorian calendar. Also use those if the date is known to be a single year in one calendar, but that stretches across two years when converted.
• If only a beginning of a date range is known, use notBefore on its own. Likewise, if only a latest possible date for the origin of the manuscript (or part) is known, use notAfter on its own.
• If a date range is between two specific known dates, use from and to attributes in the Gregorian calendar.
• If there is a gap between phases of creation (e.g. the text is 13th century then illustrations were added in the 15th) then use two origDate elements.

Don't

• Do not mark up the fact that no date is known with origDate tags. If the manuscript is completely undatable, at least to any useful degree, include a statement to that effect within the origin element.
• Do not set the calendar attribute according to the date expressed in the other attributes. These must always be Gregorian dates in order for the web site to index dates consistently for all manuscripts. The calendar should only be set to "#Gregorian" if that is how the date described in the contents is expressed.
• Do not use something like "Gregorian" for the content of an origDate or date element. If that is the placeholder in a template then replace it with something descriptive so that, if the XML tags were stripped out, it would still make sense to a reader (e.g. "1043 H, 1633-1634 CE")
• Do not use attributes such as atLeast, atMost, min, or max. These are valid, but the date-specific ones are better.

Optionally

• Use the cert attribute to record the degree of certainty of the date (the value should be one of: "low", "medium", "high", or "unknown".)
• Use the evidence attribute to indicate the nature of the evidence supporting the reliability or accuracy of the date (the value should be one of: "internal", "external", or "conjecture".)
• Use the period attribute, but this is not for the calendar. Instead its value should be a named period of time (such as the reign of a monarch or a war.)

Examples

Bad:    <origDate when="575" calendar="#Hijri-qamari">19th Ramadan 575</origDate>
Better: <origDate when="1180" calendar="#Hijri-qamari">19th Ramadan 575</origDate>
Best:   <origDate when="1180-02-24" calendar="#Hijri-qamari">19th Ramadan 575</origDate>

Bad:  <origDate calendar="#Gregorian" notBefore="1272" notAfter="1273">671 H</origDate>
Good: <origDate calendar="#Hijri-qamari" notBefore="1272" notAfter="1273">671 H</origDate>

Bad:  <origin><origDate>No date</origDate></origin>
Good: <origin>No date</origin>