Another look at namespaces

David Megginson david at
Fri Sep 17 21:20:40 BST 1999

Tim Berners-Lee writes:

 > That is not useful.  I realize that the word "Namespace" (as the
 > end result fo the discussions of modules or docuemnt types or
 > vocabularies or...)  may be an english word which does not convey
 > this, but a a namespaces is a language: a set of names plus a set
 > of syntactic constraints plus - to be useful - a meaning shared by
 > writer and recipient.

As (I think) Tim is arguing later in his message, a Namespace is a
component of a vocabulary: specifically, it's the mechanism that XML
documents use to represent (and disambiguate) the names that are part
of a vocabulary, but, as Rick argues, it's not the vocabulary itself.

Since Paul Prescod mentioned Chomsky, I'll mention Saussure: like
written or spoken words, a namespace-qualified name is a pure <foreign
lang="fr">signifiant</foreign> without any <foreign

For example, the signifier "{}apt" can be
represented by Namespaces.  The signified (say, "a valid ICAO airport
code") cannot be represented by Namespaces, but for now will probably
be represented in human-readable documentation and hard-coded in

I guess that a machine-readable schema could constrain the element to
contain up to four alphanumeric characters, but who cares, really?  My
application still has to know somehow that it's an airport code and it
has to know what it wants to do with airport codes (sell you a ticket?
give you driving directions? tell you that the document contains a
match for the code you were looking for?).

All the best,


David Megginson                 david at

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