type, role must be First Class objects (with URIs)

The XLink requirements says that "type" and "role"
"... may have meaning to specific applications":

excerpt from
http://www.w3.org/TR/NOTE-xlink-req/#general
http://www.w3.org/TR/1999/NOTE-xlink-req-19990224/#general
|4. Requirements
|
|       A: General user requirements
|
|       1: An XML link must be able to describe and relate one
|       or more Internet resources and/or data portions within
|       resources. This implies the following: 
[...]
| 4: An XML link, as an abstract datatype, must make at
|       least the following information available to an application:
[...]
| A required link type that may have meaning to
|           specific applications (if not specified, the type is
|           specifically "undefined").
|
|5: Each end of a link, as an abstract datatype, must
|       make at least the following information available to an
|       application:
|
|           A role, to specify the end's particular function in
|           relation to the link and/or the other ends. A rolemay
|           have meaning to specific applications.


In order to avoid the problem of
	does type="comment" in this document mean the same thing
	as type="comment" in that document?
type and role must be grounded in URI-space.

For more motivation, see "Web Architecture from 50,000
feet" esp:

	Also, in new developments, all significant
	objects with any form of persistent identity should be
	"first class objects" for which a URI exists. New systems
	should use URIs where a reference exists, without making
	constraint on the scheme (old or new) which is chosen. 
	-- http://www.w3.org/DesignIssues/Architecture.html

by the way... I checked, and URI there should be understood
in the RFC1630 sense, i.e. absolute URI with optional fragment
identifer; not in the RFC 2396 sense that excludes fragment
identifiers.

-- 
Dan Connolly, W3C
http://www.w3.org/People/Connolly/

Received on Monday, 19 July 1999 12:14:07 UTC