How to force valid properties & values to be set on all files being added/updated in SVN?

Is it possible to force a user who is either committing a change or adding a new file to set valid values for svn:keywords (e.g. Date, Author, & URL)?

It would be great if this behavior could be included in a pre-commit hook, preferably written in 开发者_开发技巧python.

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check this out: http://mr-ats.tigris.org/svn/mr-ats/trunk/src/hooks/property-check/

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