...on typesetters and UTF-8 terminals.
groff_man_style(7):
Portability
...
Several special characters are also widely portable. Except for
\-, \[em], and \[ga], AT&T troff did not consistently define the
characters listed below, but its descendants, like DWB, Plan 9, or
Solaris troff, can be made to support them by defining them in font
description files, making them aliases of existing glyphs if
necessary; see groff_font(5). groff’s extended notation for
special characters, \[xx], is also supported by mandoc(1), Heirloom
Doctools troff, and neatroff, but not DWB, Plan 9, or Solaris
troffs.
...
\[ha] Basic Latin circumflex accent (“hat”). Some output devices
format “^” as U+02C6 (modifier letter circumflex accent).
Notes
Some tips on composing and troubleshooting your man pages follow.
...
• Escape sequences of the form \[xx] don’t format correctly.
The \[xx] special character escape sequence is a GNU troff
extension also supported by mandoc, Heirloom Doctools troff, and
neatroff. DWB, Plan 9, and Solaris troffs don’t implement it.
If your man page requires portability to these formatters, spell
such escape sequences as “\(xx”; no closing parenthesis is used.
xx must be exactly two characters; groff_char(7) lists portable
special character identifiers.
G. Branden Robinson
561d08e53b