underspecified type-of

["Scott E. Fahlman" <Fahlman@C.CS.CMU.EDU>]

As you say, it is non-portable to assume that default structures are
vectors.  It is currently allowed for an implementation to produce
structures that are subtypes of array, though there must be some way of
telling that they are structures as well.

Several people have suggested that we should require the default
structure type to be disjoint from array, and this is on my list of
things to discuss when the current set of issues simmers down a bit.

-- Scott