[Mediawiki-i18n] Assigning tags to extension messages

[Nick White]

Hi,

I have an extension (a skin, actually, but functionally it's exactly
the same) which makes use of system messages to allow administrators
to add extra content to some areas of wiki pages. So by default the
messages are empty, and should never be translated.

You can see this in the Erudite.i18n.php change at
https://gerrit.wikimedia.org/r/#/c/62623/

I would like to mark these messages as not to be translated.
It looks like one can do this within the mediawiki core using tags;
http://www.mediawiki.org/wiki/Help:Extension:Translate/Group_configuration#TAGS

But I can't see an equivalent method for extensions. Does such a
thing exist? I plan to mention in the 'qqq' entries that they
shouldn't be translated, but it would be nice if they could be
tagged so they weren't shown in the translation interface at all.

If no such mechanism exists, what would be the best way of adding
it? Using message documentation templates, or adding the possibility
of something like a local mediawiki-defines.txt file for extensions?

I don't know the i18n code very well, so perhaps there is a
perfectly good solution I am missing.

Thanks in advance,

Nick