RFC1738 formalized URL syntax semantics and encoding to common practice in
December of 1994, not 95.
Are you trying to say that there are a significant number of documents out
there created before the RFC or common practice had settled?
Or do you mean to say that there are some newly released applications that are
not in conformance with existing interoperability specifications and that full
exploitation of those specifications should be avoided to protect a limited
number of broken, new implementations?
In any case, file URL's don't go across the network. If you are referencing a
file URL, you are most likely in control of the filesystem and the utility of
fallback locations is marginal.
-- Marc Salomon