.defs manipulation tool

[Andrei Zmievski <andrei ispi net>]

Since .defs files may sometimes be manipulated by hand to add a special
attribute - like (null-ok), for example - it seems that there is a need
for a tool that can take your modified .defs file and merge in any new
changes done to the original .defs file so that your custom changes are
preserved as the original .defs file evolves. Is there such a tool at
the present time?

-Andrei

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