advice on file locations for a package

["Steven M. Bellovin" <smb%cs.columbia.edu@localhost>]

I'm creating a package for roadmap (see
http://roadmap.digitalomaha.net/roadmap/ ).  I'm a bit puzzled by what to
do about the installation parameters in Makefile:

DESTDIR=
INSTALLDIR=/usr/local
desktopdir=$(INSTALLDIR)/applications
pkgdatadir=$(INSTALLDIR)/share/roadmap
pkgmapsdir=/var/lib/roadmap
bindir=$(INSTALLDIR)/bin
pkgbindir=$(bindir)
menudir=$(DESTDIR)/usr/lib/menu
ICONDIR=$(INSTALLDIR)/share/pixmaps
mandir=$(INSTALLDIR)/share/man
man1dir=$(mandir)/man1

Clearly, INSTALLDIR is $(PREFIX) (though I confess I don't know how to
parameterize $(PREFIX) in a patch file).  I believe that desktopdir should
be $(PREFIX)/share/applications and pkgdatadir $(PREFIX)/share/roadmap.
pkgmapsdir should probably be $(pkgdatadir)/maps.  I have no idea what
menudir is; it seems to be some gnomish thing.  It's only used if it
exists.  What should I set ICONDIR to?  

A separate issue is that this software can run with gtk, gtk2, and qt3;
for now, I'm going to build the gtk2 version and let someone else
parameterize it.

                --Steven M. Bellovin, http://www.cs.columbia.edu/~smb