> I was wondering if some kind of pre-processor existed back in the time
Yes, "form" and "fed", a form-letter generator and editor, were in the 2nd through 6th editions of Unix. Created by Bob Morris and Lorinda Cherry, they were independent of roff, but could of course could produce roff input. You can find their man pages and perhaps their source code in the Unix Archive at www.tuhs.org. (Bear in mind that both man macros and C were different back then.) Bob Morris used it to patch boilerplate comments into journal referee reports: sentences such as, "Related work, in particular ]1], should be cited." with [1]" and "This paper manuscript presents a known result, previously published in [2]". The referee reports themselves were kept in the same repository. The system reminded me of Vannevar Bush's Memex proposal, but other uses did not materialize and it died of neglect. Doug
