[mpeg-OTspec] Conflicts between language system tags

[Andrew Glass (WINDOWS)]

Thank you for raising this issue Vlad.

Following a discussion with Peter, we’d like to propose using an marker (perhaps “6” for ISO 639-3) in the language system tag to identify new codes that are based on ISO 639-3. The rest of the tag would be the upper-cased ISO tag, per Bob’s mail.

What should the marker be?
                The value of the marker is arbitrary. Using a number would make it clear which portion of the language tag is taken from ISO 639-3. The suggestion is to use 6 since this is the first digit of the number of the standard. 3 might be another option.

Should the marker be used on all future tags, or just those that have a conflict with an existing tag?
                The tag is only really necessary in order to resolve a conflict with an existing tag. Most current ISO 639-3 codes could be safely brought into the current OTSpec without conflict. Therefore, including the marker everywhere is unnecessary. However, by using the marker generically the OTSpec itself need not be updated every time a language is needed. Rather, the full set of ISO 639-3 language codes would become available by the introduction of the marker.

Should the marker come at the beginning or end of the tag, 6KAB or KAB6?
                If the marker is used at the beginning, then it is easier to parse forwards, so the next three bytes are an ISO 639-3 code. If the marker is at the end of the tag, then they will interleave with the existing OT Language tags when sorted.

Andrew


From: mpeg-OTspec at yahoogroups.com [mailto:mpeg-OTspec at yahoogroups.com] On Behalf Of Bob Hallissy
Sent: 25 February 2013 10:46
To: OTspec (mpeg-OTspec at yahoogroups.com)
Subject: Re: [mpeg-OTspec] Conflicts between language system tags



Is it an option to freeze the existing language tags and then to bump
the GSUB/GPOS table version and declare that in the new version all tags
are, for example, ISO 639-3 (maybe the upper-case thereof) ?

Bob

On 2013-02-25 at 11:35 Levantovsky, Vladimir wrote:
> I am afraid that in the future, as we attempt to add more languages
> supported by the OT/OFF standard we may see this situation repeated
> when some of the tags already in use may conflict with the new tags
> defined according to ISO 639 standard. Therefore, I would suggest that
> we need to come up with a solution that would allow us reconcile the
> differences between OT language system tags and ISO 639 language tags.
> It is clear that for all newly defined languages new system tags
> should be based on ISO 639 tag; however, we need to find a systematic
> way that would allow us to resolve the existing and, potentially,
> future conflicts.

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