I'm digging through Groff's source, and I found this puzzling acronym littered throughout tmac/doc-common-u:
.\" NS Dd user macro (not parsed, not callable) .\" NS set document date .\" NS .\" NS modifies: .\" NS doc-date-string .\" NS doc-command-name .\" NS .\" NS local variables: .\" NS doc-date-XXX .\" NS .\" NS width register `Dd' set above My first guess was it had something to do with comment-stripping for distributed tmac files, but that wouldn't explain why unprefixed comments are stripped too. The description of the .HTML-NS macro (in tmac/www.tmac.in) would suggest something debugging-related: .\" .\" An auxiliary macro for HTML (without following space). .\" .de HTML-NS . nop \X^html:\\$*^\c ..
