Package “gnustep-make” has 3 man pages.

The openapp command allows you to launch graphical GNUstep applications from the command line. application is the complete or relative name of the application...
opentool is obsolete. You should make sure that the Tools directories are in your PATH, and then opentool is not needed anymore.
This manual page is about cross-compilation and fat binaries. Fat binaries are packages that you can supply which contain more the one binary of your program...