[developers] type addenda and :< in TDL

[Francis Bond]

G'day,

> Recently I have been playing with type addenda (using :+) to make some
> systematic changes to LE types (so far in ERG only).  I've run in to a few
> cases where the original type was defined with :< rather than :=, and hence
> won't allow modification.  This seems to be by design, since the distinction
> is built in to both LKB and PET, but I'm not sure if it is still intended to
> mean such.  My initial queries to Those Who Know said that := and :< are
> equivalent, and :< is a historical artifact.
>
> Is there anyone currently using :< to mean 'don't allow features on this
> type' (or to mean anything else)? Is there any reason to keep this
> distinction?

My understanding is also that ":<" is deprecated, and that we were all
being encouraged to move to ":=".  Perhaps you could provide Dan with
a patch for the ERG?


-- 
Francis Bond <http://www2.nict.go.jp/x/x161/en/member/bond/>
NICT Language Infrastructure Group