SAX2: Namespace separators

Andrew Layman andrewl at
Wed May 19 23:34:11 BST 1999

RDF concatenates a namespace's URI plus a local name to form a new URI by
simple concatenation, with no intervening separator, true enough, but RDF
also imposes a rule that all namespace URIs must end in "/" so that no
ambiguity is possible.

I think there are two lessons to take from this:

1.	It is desirable, perhaps essential for RDF compatibility, that the
composition of a namespace's URI plus a local name itself be a URI or URI

2.	Careful choice of rules for either naming namespaces or for picking
separator characters allows us to avoid ambiguity.

Proposals to never have a separator either lead to ambiguity or to imposing
restrictions on namespaces. These, therefore, either fail the ambiguity test
or fail in the face of many namespace URIs that are legal per the namespaces
spec.  That is not good.

I have seen the following rule proposed, and it appears both robust and
compatible with RDF:

To compose a namespace's URI plus a local name into a new string that is a
URI reference, concatenate the strings directly if the URI ends in "/" or
"?", else concatenate the strings but separate them with a "#".

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