The valid format for the mfpp command is:
mfpp [–ipath dir][-{isuffix|x} suffix] [–pp outfile]infile
where dir is a directory name, suffix defines a string to be appended to any unquoted filename in a %INCLUDE statement, infile specifies a source filename, and outfile specifies an output filename. At least one input file must be specified.
The preprocessor input is a file containing an Open PL/I source module, possibly including Open PL/I Macro Preprocessor statements. The preprocessor output is an Open PL/I source module containing no further preprocessor statements, but with the source code modified according to the semantics of the preprocessor statements that were encountered in the input file.
mfpp is usually run by use of the -macro option with mfplx.