ambiguity around month "code" vs tag

[dthaler]

extensions.ged has an extension tag (_JOUR) with a standard calendar (FRENCH_R):

2 TAG _JOUR https://gedcom.io/terms/v7/month-COMP
...
2 CONT Standard month with an extTag            ... FRENCH_R 2 _JOUR 8
...
2 DATE BET FRENCH_R 2 _JOUR 8 AND _CALENDRIER 4 COMP 8

Section 2.4 (Date) of the GEDCOM spec says:

month   = stdTag / extTag  ; constrained by calendar

Section 6.1 (Known Calendars) says, under FRENCH_R:

Permitted months are:
(list that includes `COMP` but not `_JOUR`)

Taken together, this can be read as saying that the FRENCH_R calendar constrains the set of month tags as only permitting ones in the table in section 6.1, such that extension tags are not permitted.

Does the extensions.ged file have an invalid test case or does the spec need to be updated?

[dthaler]

Discussion during GEDCOM Steering Committee meeting 19 NOV 2024: The following Section 6.1 text is relevant:

Month codes in extension calendars must either be already used for the same month name in another calendar or must start with _. ... Each month defined in this section has a URI constructed by concatenating g7:month- to the month code; for example, the month of Elul has the URI http://gedcom.io/terms/v7/month-ELL.

• We cannot find anywhere in the spec that says what the "month" production in ABNF refers to in the Known Calendars section. The text at the top of 6.1 says code is a URI suffix and says nothing about whether it's the same as a tag.
• The text quoted above also only refers to months "defined in this section" and not a constraint on extension calendars.
• We are thinking of changing the tables in section 6.1 to have 3 columns: standard tag, URI, and name (and getting rid of "code" as a term).