[docbook-tc] unique identifiers for XML character entities?

I'm wondering whether version numbers of some kind should be included
in the XML character entity files. Maybe just an RCS $Id keyword at
least.

I mention it because I tried installing a package distribution that
was recently created for installing (among other things) the DocBook
DTDs and XML characters entities on the Cygwin[1] system for Windows.

The iso-num.ent entity file in that distribution had been altered by
somebody along the way -- to comment out the declarations for the "lt"
and "amp" entities.

I think having a version number in the files -- along with some
statement that these are standard declarations that should not be
altered -- would help to identify them as "official" and help to
prevent anyone from being tempted to tamper when them when they
distribute them.

  --Mike