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Subject: RE: [docbook] URN for Simplified DocBook and DocBook XML
I have been evangalizing canonical URLs for system identifiers among SGML docheads (usually, they don't quite seem to get it). And I've proposed an easy-to-use scheme for mapping canonical URLs to the local file system [1]. But to be true, I think the XML Specification is flawed in requiring a system identifier. "System identifier should always work" -- why? This is naïve -- they should, but hey, they don't always work correctly, or at all. Uncertainty is something to be avoided in a production environment. Sometimes, I specifically don't want a document to work without entity resolution through catalogs -- my catalogs. Just as in the good ol' SGML days. [1] http://lists.oasis-open.org/archives/docbook-apps/200210/msg00038.html -- \|/ <@ @> Peter Ring +-oOO-(_)-OOo--------------------------- | Address Palægade 4 | P.O.Box 9026 | DK-1022 København K | Phone +45 3396 0153 | Fax +45 3396 0101 | EMail pri@magnus.dk | WWW www.magnus.dk -----Original Message----- From: Jirka Kosek [mailto:jirka@kosek.cz] Sent: 6. maj 2003 16:43 To: Peter Ring Cc: docbook@lists.oasis-open.org Subject: Re: [docbook] URN for Simplified DocBook and DocBook XML 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 -- ----------------------------------------------------------------- Jirka Kosek e-mail: jirka@kosek.cz http://www.kosek.cz
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