@code{ptx}: Produce permuted indexes
-* General options in ptx:: Options which affect general program behaviour.
+* General options in ptx:: Options which affect general program behavior.
* Charset selection in ptx:: Underlying character set considerations.
* Input processing in ptx:: Input fields, contexts, and keyword selection.
* Output formatting in ptx:: Types of output format, and sizing the fields.
Upon any error, @code{sort} exits with a status of @samp{2}.
@vindex TMPDIR
-If the environment variable @code{TMPDIR} is set, @code{sort} uses its
+If the environment variable @env{TMPDIR} is set, @code{sort} uses its
value as the directory for temporary files instead of @file{/tmp}. The
@samp{-T @var{tempdir}} option in turn overrides the environment
variable.
All 256 characters, even @kbd{NUL}s, are always read and processed from
input file with no adverse effect, even if GNU extensions are disabled.
However, System V @code{ptx} does not accept 8-bit characters, a few
-control characters are rejected, and the tilda @kbd{~} is condemned.
+control characters are rejected, and the tilde @kbd{~} is condemned.
@item
Input line length is only limited by available memory, even if GNU
@subsection Warning messages
@vindex POSIXLY_CORRECT
-Setting the environment variable @code{POSIXLY_CORRECT} turns off the
+Setting the environment variable @env{POSIXLY_CORRECT} turns off the
following warning and error messages, for strict compliance with
@sc{POSIX.2}. Otherwise, the following diagnostics are issued: