DTV12 — Starting week day is a number

Specification: DTV v1.1

Title: Starting week day is a number

In clause 12.4, the entry for starting week day has the Definition:

the index of the Gregorian day of year that is 3 days before the first Thursday of some Gregorian year

It is at least unexpected that any category of ‘day’ would be a integer. The definition appears to be that of ‘starting Monday index’, or something the like. The expected concept would be “Gregorian day that is three days before the Gregorian day that corresponds to the first Thursday of the Gregorian year.’ In either case, one would have to define: Gregorian year has first Thursday. This suggests that the useful concept is in fact, Gregorian year has starting Thursday (or starting Monday).

The verb concept is ‘starting week day of Gregorian year’ rather than ‘Gregorian year has starting week day’, and there is a Necessity that only Gregorian years after 1600 have starting week days, which is clearly wrong.

This whole concept appears to be an artifice for determining which week of the ‘weeks calendar’ is the ‘first week’ of a Gregorian year. So there is no intended business use of these terms, but the entries should be corrected.

The last paragraph of the Issue Summary correctly indicates that the function of ‘starting week day’ is to support interpretation of ‘week of year’ and ‘year week coordinates’. The resolution of Issue 19574 restructures that interpretation by creating a fixed relationship between the Gregorian calendar and the weeks calendar. That restructuring eliminates the use of ‘starting week day’ per se, although it makes a similar concept ‘first Thursday’ necessary.
The resolution of this issue is therefore merged with that of 19574.
Revised Text:
none. See Issue 19574