[Groff] extended .bd syntax

[Werner LEMBERG]

Dear groffists,


I've found another undocumented gem in GNU troff's treasure chest:

  .bd font1 font2 n

This will embolden FONT1 by N units if FONT2 is active.

Use this in combination with special fonts (either set up with the
`special' keyword in a font file or with the `.fspecial' request).

Try the following with the PS device:

  .bd SS R 10p
  .bd SS I 20p
  .
  .ft R
  This is a pi:\[*p].

  .ft I
  This is a pi:\[*p].


    Werner