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

Chapter 2: Invoking groff 11
X75-12 For a 75 dpi X11 previewer with a 12 pt base font in
the document.
X100 For a 100 dpi X11 previewer.
X100-12 For a 100 dpi X11 previewer with a 12 pt base font
in the document.
ascii For typewriter-like devices using the (7-bit) ASCII
character set.
latin1 For typewriter-like devices that support the Latin-1
(ISO 8859-1) character set.
utf8 For typewriter-like devices which use the Unicode
(ISO 10646) character set with UTF-8 encoding.
cp1047 For typewriter-like devices which use the EBCDIC
encoding IBM cp1047.
lj4 For HP LaserJet4-compatible (or other PCL5compatible)
printers.
lbp For Canon CAPSL printers (LBP-4 and LBP-8 series
laser printers).
html
xhtml To produce HTML and XHTML output, respectively.
Note that this driver consists of two parts, a preprocessor
(pre-grohtml) and a postprocessor (postgrohtml).
The predefined gtroff string register .T contains the current
output device; the read-only number register .T is set to 1 if
this option is used (which is always true if groff is used to call
gtroff). See Section 5.6.5 [Built-in Registers], page 77.
The postprocessor to be used for a device is specified by the
postpro command in the device description file. (See Section 8.2
[Font Files], page 204, for more info.) This can be overridden
with the ‘-X’ option.
‘-U’ Unsafe mode. This enables the open, opena, pso, sy, and pi
requests.
‘-wname’ Enable warning name. Available warnings are described in
Section 5.33 [Debugging], page 179. Multiple ‘-w’ options are
allowed.
‘-Wname’ Inhibit warning name. Multiple ‘-W’ options are allowed.
‘-v’ Make programs run by groff print out their version number.
‘-V’ Print the pipeline on stdout instead of executing it. If specified
more than once, print the pipeline on stderr and execute it.