This is a PPWIZARD command line switch.
This switch allows you to specify one or more files which should automatically be included before any other file processing takes place.
To specify more than one they should be separated by a ';' character (or ':' under unix). Any files that you specify are added to the any you may have previously specified.
Rarely you may wish to reset the current list of include files, to do this don't pass any parameters.
You could use this if you supply a set of macros in header file and supply a batch file to run the preprocessor. You would then not have to require (or request) a user of your header to '#include' it themselves.
Note that "/Include" is an alias for this command (v02.001+).
ppwizard *.it /output:out\*.htm /CrLf /#Include:Header1.H;Header2.H