$^W The current value of the warning switch, initially true if -w was used, false otherwise, but directly modifiable.

$^N The text matched by the used group most-recently closed (i.e. the group with the rightmost closing parenthesis) of the last successful

$EFFECTIVE_USER_ID

$> The effective uid of this process. For example: $<

$INPLACE_EDIT

$OUTPUT_FIELD_SEPARATOR

$WARNING

$FORMAT_TOP_NAME

$DEBUGGING

$FORMAT_FORMFEED