Re: Generic Tagging: A Modest Proposal

From: Kenneth Whistler (
Date: Mon Jul 14 1997 - 18:03:26 EDT


Your generic tagging proposal is interesting. Something
fairly similar is in the works, using a set of
metacharacters to spell out tags. The currently
active proposal is called the "Plane 14" proposal,
and has been in active discussion between the UTC
and members of the IETF.

The main differences from your proposal are:

1. For simplicity and generality, an entire set of
95 ASCII metacharacters are provided, instead of just
A-Z, 0-9, hyphus and space. This retains the
transparency of characters, as in your proposal, but
allows us to set up a scheme that will also be easy
to debug or to redisplay as ASCII values for tags.

2. The tagging mechanism is set up on Plane 14 instead
of the BMP. Although this makes the tags longer than
would assignment to the BMP, it avoids conflicts with
to Roadmap for assignment of scripts and other characters
to the BMP.

3. Rather than introducing a completely generic public
tag scheme, with a path characters, reversed domain
names, and then arbitrary tags per domain, we concluded
that there was really only a clamor for a couple of
kinds of tags: language tags and character source set
tags. Maybe one or two others might be useful. So we
introduced particular tag types rather than a completely
open mechanism. There is also a private tag introducer
which makes it possible to have arbitrary private tagging

4. The Plane 14 proposal also provides more information
about the scope of tags and the cancelling of tag values.

The UTC will be considering the Plane 14 proposal in its
meeting next month, at which point we should know whether
it will prove acceptable for Unicode or will have to
be amended in some way.

--Ken Whistler

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