Request for variant subtag fr 16th-c 17th-c Resubmitted!

Mark Davis mark.davis at
Tue Dec 19 03:35:27 CET 2006

Peter, I'm a little bit fuzzy on where the lines were drawn with historic
versions of the same language in ISO. This is relevant to the LTRU group for
ISO 639-3, so am cc'ing that group.

I take it from your discussion that "fr" means *only* modern French, and
that if I want to have a tag for any French, modern or not, I would have to
use (fr OR frm OR fro). Similarly, if I wanted any English, I would have to
use (en OR enm OR ang).

My question is how this is managed over time in ISO, since there are
significant implications for language tags. Let's take Czech, for example,
where we only currently have 'cs'. I see the following possibilities.

1. This means only Modern Czech.
That implies that there is no code for Old Czech, so if I want to tag
something with that, I need to petition ISO for an language tag for Old
Czech (let's say 'ceu'). Once that is added, I can refer to Old Czech.

2. This currently means any Czech, but ISO may introduce a code for Old
Czech (let's say 'ceu'). I see three possible approaches:

2a. The denotation of 'cs' is changed to mean only modern Czech. This would
be a breaking change for the language subtag registry, since the meaning of
a subtag would be narrowed, invalidating any tags that had a broad
application. This would be rather disturbing, since we are guaranteeing

2b. The denotation of 'cs' remains "any" Czech, and to get only modern Czech
I would need to use (cs AND NOT ceu). Note while OR can be handled with a
list, as per RFC 4647, AND NOT cannot. This, however, would not break

2c. The denotation of 'cs' remains "any" Czech, ceu becomes an extlang.
This I see as the least unpleasant outcome, but I can't tell if whether this
would be the ISO policy.

While I use Czech as an example, the same would be true for any similar
breakdown, including English into Early Modern and Modern.

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