I'm looking for the guidelines on the proper usage of the make variables 
WARNING_MSG and ERROR_MSG.  When should they be used?  For example, I'm 
rewriting some of the install targets, and they have a check the package 
isn't already installed.  Currently if the package *is* already 
installed, then the error is reported to the user using ${ECHO_MSG}, i.e.:

===> digest-20060302 is already installed - perhaps an older version?
*** If so, you may wish to ``pkg_delete digest-20060302'' and install
*** this package again by ``/usr/bin/make bin-install'' to upgrade it
*** properly.

Should this be changed to use ${ERROR_MSG} instead because this a fatal 
error?

	Thanks,

	-- Johnny Lam <jlam@pkgsrc.org>