In3 uses a groff macroset in.tmac to provide functionality that in3 needs, but is not offered by the standard mm or mom macrosets. The in.tmac macroset is an adaptaion of the mgm macroset.
Much of the use of the in macros will be hidden by the xml3roff preprocessor. Most of the time, the use will be limited to the definitions in stylesheet.mm.
.ds pg*header '' in3 '' .ds pg*footer ''- \\nP -''
.NOHEAD .nr Ej 1 .ds HF HB HB HI HI I I I .ds HP 16 12 12 0 0 0 0 .nr Hb 4 .nr Hs 1 .nr Hps 0 .ev classtest .ll 6i .in 3i .gcolor red .ev