W3C home > Mailing lists > Public > uri@w3.org > January 2000

URI terminology, esp. in XML specs

From: Dan Connolly <connolly@w3.org>
Date: Mon, 10 Jan 2000 09:34:58 -0600
Message-ID: <3879FC22.7A86AA5F@w3.org>
To: uri@w3.org
I have recently spent a considerable amount of time studying
the URI spec
[1]	http://www.ietf.org/rfc/rfc2396.txt
and I discovered, somewhat to my surprise, that it
defines the terms "URI reference" and "absolute URI" very precisely,
but
        (a) it doesn't define the term "URI", syntactically (!!!)
and
        (b) it doesn't give a term for an
absolute-URI-with-optional-fragment-id , i.e. the result of combining
a URI reference with an absolute URI.

This is pretty awkward, since an absolute-URI-with-optional-fragment-id
is
really what we meant when we wrote "URI reference" in:

"An XML namespace is a collection of names, identified by a URI
reference"
-- http://www.w3.org/TR/1999/REC-xml-names-19990114/#sec-intro

We used "URI reference" because "absolute URI" excludes fragment
identifiers,
and we wanted
	http://example.net/#vocab
to be a valid namespace identifier.

But
	../xyz/
isn't a namespace identifier, until you combine it with a base
absoluteURI.

Another example:

"The locator attribute provides a URI-reference that identifies a remote
resource (or sub-resource)"
-- http://www.w3.org/TR/1999/WD-xlink-19991220/#Local Resources for an
Extended Link

URI-references don't identify remote resources; absoluteURIs do. The
"or sub-resource" makes it clear that the author intends to allow
#fragids.
So again, what's needed is a term for
absolute-URI-with-optional-fragment-id.

It was called fragmentaddress in RFC1630.
http://www.ietf.org/rfc/rfc1630.txt



If formal systems float your boat, you can take a look at my formalism
of this stuff in larch:
        http://www.w3.org/XML/9711theory/URI
        http://www.w3.org/XML/9711theory/URI.html (HTML version with
                nasty hacks for math symbols)
        http://www.w3.org/XML/9711theory/URI.lsl (original ascii LSL
version)

part of
        "Specifying Web Architecture with Larch"
        http://www.w3.org/XML/9711theory/

which gives pointers explaining larch etc.


I used the term URIwf for absolute-URI-with-optional-fragment-id, and
I used absoluteURI and URI_reference with their rfc2396 meanings.


-- 
Dan Connolly
http://www.w3.org/People/Connolly/
Received on Monday, 10 January 2000 10:35:29 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Thursday, 13 January 2011 12:15:26 GMT