Similary the undocumented postgresism of interpreting
INTERVAL '1:02'
as 1 hour 2 minutes is consistent with the ANSI
INTERVAL '1:02' HOUR TO MINUTE
but not with the ANSI
INTERVAL '1:02' MINUTE TO SECOND
which of course means 1 minute 2 seconds.
The fact is that ANSI interval syntax is very different from postgres
interval syntax. In ANSI interval syntax the literal string can only
be interpreted in the context of the interval type; in postgres
interval syntax the literal string has a well defined meaning in and
of itself, and no interval type is explicitly declared.
So I think I'm back to where I started. Attempting to define
semantics for a hybrid format, where you have an ANSI interval type
but the literal string formatted in postgres interval format is
unnecessarity confusing and complicated.
-roy