The Heirloom Documentation Tools provide troff, nroff, and related
utilities to format manual pages and other documents for output on
terminals and printers.  They are portable and enhanced versions
of the utilities released by Sun as part of OpenSolaris, and, for
pic, grap, mpm, and some minor parts, by Lucent as part of Plan 9.

Homepage:
https://n-t-roff.github.io/heirloom/doctools.html
