xml-dev - Re: ID's in a document ?

[Robin LaFontaine <robin@monsell.co.uk>]

As Curt says, XML Schema is the only way to do this, it cannot be 
specified within a DTD. See also discussions "Inserting optional 
elements" last week on this list for some further discussion of this 
issue. NewsML DTD has introduced a "Euid" (element unique id) for 
this purpose: it is just a CDATA or NMTOKEN attribute that is unique 
within the context of the parent element. For repeated items it is 
good practice to have such a 'handle' on the data, as you are 
suggesting, and IMHO it is best to make it required.

Robin


>Hello,
>
>I am new to XML and this list. I found that id's in a xml document
>are have to be unique in the document. But I need an id for a specific
>area (subtree). The XML specification does not describe such a
>posibility.
>
>Is there any solution about this ?
>
>I begun with my workaround, but it is not good to implement that, if
>it is already implemented anywhere.
>
>My Idea for an implementation is this:
>
>On the root of a subtree define an attribute like LOCID pointing to a
>tagname, that must contain such a local id identifer.
>
>In that tag define an IDPTR pointing to an attributename, that should
>be the local id.
>
>Thia can be defined in a dtd file and the parser can handle this
>regardless what type of document is being parsed.
>
>So his may be handled by the sax parser.
>
>Is that possible ?
>
>I hope, my first question is not a bad one :-)
>
>Thanks
>
>Lothar
>
>--------------------------------------------------------
>Lothar Behrens    | Company: lothar.behrens@giquadrat.de
>Borsteler Bogen 4 |     C++ is the future, LINUX too :-)
>22453 Hamburg     |     have a look at www.wxWindows.org

-- -----------------------------------------------------------------
Robin La Fontaine, Monsell EDM Ltd
(Engineering data exchange and management using XML, R&D Project Management)
Tel: +44 1684 592 144 Fax: +44 1684 594 504
Email: robin@monsell.co.uk       http://www.monsell.co.uk