Date: Mon, 20 Dec 2004 14:28:52 +0100
From: Harald Tveit Alvestrand <harald@xxxxxxxxxxxxx>
Message-ID: <55A053496CEEFA928DC9B120@B50854F0A9192E8EC6CDA126>
| In general, any time you have a set of values that can change over time,
| and there is a reason for the community to know the currently-valid set of
| values, a registry is a Good Thing.
The one caveat is that the set of values needs to be stable enough
that maintaining a registry makes sense.
To take one example of the contrary case - multicast group IDs.
There is an IANA registry of blocks and their uses, and a few specific
groups - but most groups come and go with no registry (IANA registry)
action at all.
And yet, both conditions as stated by Harald are met - there is a set
of values that change over time (obviously) and the community have
reason to know the current set of values - both so they know what a
particular value maps into (so they can join the appropriate group),
and so they know what values are free (so an appropriate identifier can
be selected for a new group).
Yet an IANA registry of such values would not be a good thing, they often
survive for less time than it would take to get the registry updated - that
is, by the time the update could be done, the updated data is already
obsolete.
kre
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