The original source code was developed using the CVS revision control system, but only one "tagged" version of the model is available within any source code distribution. This information can be used to identify the code contained in a particular distribution. A user may wish to modify their copy of the model code.
The source code is written almost entirely using standard Fortran 77. Perhaps the most notable exception is the use of the library calls "msread" and "mswrite" which rely on NCAR's site specific Mass Storage System (MSS) for storing large output files. The use of the model on non-NCAR computers will necessitate code modification of the source code to remove such site specific or machine specific code. Searching for preprocessor "if-defs" (e.g. "#if (defined CRAY)") in the source code files should lead you to the code which is not standard Fortran.