Re: [docbook] URN for Simplified DocBook and DocBook XML

[Jirka Kosek <jirka@kosek.cz>]

Peter Ring wrote:

> Sometimes, I like to use URNs for system identifiers in XML files; this
> ensures that entity resolution goes through my catalog files, and not to
> random files in the file system or on the net.

This is not good practise IMHO. System identifier should always work and 
thus you should use URL pointing to the publicly available resource. All 
catalog implementation which I know allow you to override also system 
identifiers so you can gain benefits of catalog files on your local 
system and still your document work also without any catalog at all.

So I will recommend you to use following URL

http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd

as a system identifier and then put something like

<system
    systemId="http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
    uri="/path/to/your/local/copy/of/docbook/dtd/docbookx.dtd"/>

into your catalog file.

Using URN is a very good practise in many places (e.g. namespace 
identifiers) but not in system identifiers. System identifier must be 
always resolvable, and this can't be guaranteed with URN.

				Jirka


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   Jirka Kosek  	
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