[Groff] Passing -D argument to grap on groff command line?

Hello, I realize that it is possible to use the environment variable GRAP_DEFINES to pass the name of the grap definition file to grap, but I'd really like to be able to do this from the groff command line. How do I do this? The groff "-P" option seems to pass arguments on to postprocessors onl

Re: [Groff] Passing -D argument to grap on groff command line?

> I realize that it is possible to use the environment variable > GRAP_DEFINES to pass the name of the grap definition file to grap, > but I'd really like to be able to do this from the groff command > line. How do I do this? The groff "-P" option seems to pass > arguments on to postprocessors o