As of ROMS 2.0 Der Mouse's CPP code is no longer neccessary.
versions prior to 2.0 use extensive C-preprocessing to configure its various numerical and physical options. The parallel design of the code for both shared- and distributed memory computers is managed also with CPP
definitions. This often requires more than one replacement in a single line of code which is not allowed by the default /lib/cpp in some platforms. We found out that this not a problem on SGI platforms but it does not work in SUN platforms. In order to solve this portability problem, we provide a CPP code
written by Der Mouse that offers multiple macro replacements and other extra features. Users
just need to compile this special CPP software and place it in their $HOME/bin
directory or specify the complete path for it in the Makefile.