by Trent A. Fisher and Werner Lemberg - The GNU Operating System

30 The GNU Troff Manual
.Ds
Begin a non-filled display.
.De
End a non-filled display started with Ds.
[Macro]
[Macro]
.EX [indent]
[Macro]
Begin a non-filled display using the constant width (Courier) typeface.
Use the optional indent argument to indent the display.
.EE End a non-filled display started with EX.
[Macro]
.G [text]
[Macro]
Set text in Helvetica. If no text is present on the line where the macro is
called, then the text of the next line appears in Helvetica.
.GL [text]
[Macro]
Set text in Helvetica Oblique. If no text is present on the line where
the macro is called, then the text of the next line appears in Helvetica
Oblique.
.HB [text]
[Macro]
Set text in Helvetica Bold. If no text is present on the line where the
macro is called, then all text up to the next HB appears in Helvetica Bold.
.TB [text]
Identical to HB.
[Macro]
.MS title sect [punct]
[Macro]
Set a manpage reference in Ultrix format. The title is in Courier instead
of italic. Optional punctuation follows the section number without an
intervening space.
.NT [C] [title]
[Macro]
Begin a note. Print the optional title, or the word “Note”, centered on
the page. Text following the macro makes up the body of the note, and
is indented on both sides. If the first argument is C, the body of the
note is printed centered (the second argument replaces the word “Note”
if specified).
.NE End a note begun with NT.
[Macro]
.PN path [punct]
[Macro]
Set the path name in constant width (Courier), followed by optional punctuation.
.Pn [punct] path [punct]
[Macro]
If called with two arguments, identical to PN. If called with three arguments,
set the second argument in constant width (Courier), bracketed
by the first and third arguments in the current font.