http://norman.walsh.name/2004/04/06/cvsdates 7 57 2004-04-06T17:43:00-04:00 $Date$ Norman Walsh 2004 Norman Walsh The CVS $Date$ keyword doesn’t validate as an ISO 8601 date/time. Samuel Johnson Men are generally idle, and ready to satisfy themselves, and intimidate the industry of others, by calling that impossible which is only difficult. I’ve been working more-and-more with DocBook NG. Mostly I’m pretty satisfied, but it’s definitely not without surprises. Handling “universal linking” has turned out, for example, to be tricky. It’d be easier with XSLT 2.0, but I’m not ready to make that commitment yet. I mean literally not ready, I still have extension functions that don’t run in Saxon 7. The formatting issues are mostly a matter of intellectual effort, the right answer is clear even if the solution that produces it isn’t. Here’s something more interesting: what constraints should be placed on the content of elements that are clearly supposed to hold dates and times? In “Bourbon”, the content of date and pubdate are constrained to be dates in the following way: db.pubdate = element date { date.attlist, (xsd:date | xsd:dateTime | xsd:gYearMonth | xsd:gYear) } Works for me, until I discover that I routinely (ab)use date in the following way: <date>$Date$</date> That’s clearly a date, but it doesn’t validate. Yet I still want the date element to contain the last modified date as provided by CVS. So what to do? On one end of the spectrum, we could decide that DocBook will not attempt to constrain the content of the date elements. On the other end, we could enforce the constraint and I could move my CVS keyword-based date off into some other element, perhaps one in my own namespace. For the moment, since this is all in a customization layer (specifically, the “NG” version of the schema for this weblog), I worked around the problem by providing another pattern for date and allowing it in the info: cvsDate = element date { date.attlist, xsd:string { pattern = "$Date: \p{Nd}{4}/\p{Nd}{2}/\p{Nd}{2} \p{Nd}{2}:\p{Nd}{2}:\p{Nd}{2} $" } } Gotta love the flexibility of RELAX NG. Thoughts?