RFPP is a portable ratmac-to-Fortran77 preprocessor that has been developed primarily for use with the Xtal System of Crystallographic Programs, and the Qchem quantum chemistry package (Favas & Hall, 1989). It is, however, applicable to any large-scale software development where portability and efficiency are important.

RFPP is superior to earlier ratfor and ratmac preprocessors. The fundamental difference is that RFPP converts ratmac into structured Fortran77. The RFPP source is extensively commented, and employs Fortran77 character 'substring' notation. RFPP employs a restricted character set (see the section called “RFPP character set ”) which provides compatability with ASCII or ebcdic installations. This allows characters supported on the local machine to be processed transparently.

A description of RFT, the ratmac 'tidy' program, has been given in the Installation section. RFT performs a number of useful checking functions and improves the readability of the code. Because it ensures that RFPP will operate efficiently, its periodic application during the development of a ratmac program is recommended.