Mutt made me believe that Greg A. Woods wrote:
>      If the package contains a require file (see pkg_create(1)), then this is
>      executed first as
>            require <pkg-name> DEINSTALL
>      (where pkg-name is the name of the package in question and DEINSTALL is a
>      keyword denoting that this is a deinstallation) to see whether or not de-
>      installation should continue.  A non-zero exit status means no, unless
>      the -f option is specified.
> 
> (though obviously you have to write a REQUIRE script too  :-)

Just for the record:
In pkgsrc, they REQ files we had have been deprecated for
INSTALL/DEINSTALL ones. (i.e. no more support for them in bsd.pkg.mk).
The support in pkg_* hasn't been removed for historical reasons (you
could still have a binary package of one of the four packages that
used a REQ file.)

Bye,
 Thomas

-- 
Thomas Klausner - wiz@danbala.tuwien.ac.at