systemheader: is used to tell the preprocessor that a new program subunit has started, and serves to separate and identify program subunits output to the Fortran file. The precise function of systemheader: is set with the definition of the RFPP macro sys:. Typically systemheader: generates a comment line at the start of each Fortran subunit. For some operating systems it may also be used to partition the output file into subfiles. The ratmac tidy routine RFT also uses systemheader: to initiate its line-labelling operation.

systemheader:(IDcode, key)

IDcode is the alphanumeric identifier code of lines that follows systemheader: key is a flag to distinguish headers of 'active' code (e.g. ratfor source) from 'inactive' code (e.g. macro definitions). The key is usually set to blank and '*', respectively, for these purposes.

Note that RFPP also uses the IDcode in the summary line output when an END line is detected. See the source code of RFPP and RFT for examples.