On Saturday, 4 June 2022 22:44:10 BST Dave Kemper wrote: > On 6/4/22, James K. Lowden <jklow...@schemamania.org> wrote: > > A "zero width space" is perfectly clear terminology. > > Not to anyone familiar with Unicode's U+200B ZERO WIDTH SPACE, which > doesn't correspond to groff's \& but to its \: (which groff currently > calls the "non-printing break point"). And regardless of who can > claim the longer history, Unicode terminology is in much wider use > today than CSTR#54 terminology.
I think all users will know what a space is, then we have all different width of spaces, 1/6 of an em, 1/12th an em, size of a digit, and also a zero width space. People who know nothing about Unicode or CSTR#54 will know about spaces, and whilst a zero space may not initially seem useful, I bet the Romans wished they had one. There are several escapes where the input (the escape) results in a movement in the current position rather than a mark on the page. \& is just a movement of zero. There are other escapes which could be called "non-printing input break" since they can achieve the equivalent, consider:- echo "\\Z''.sp" | nroff You should see the text ".sp". Any escape with zero movement acts in this way, it is not special to \&. The difference is that \& is the shortest escape which causes no movement, so is useful for this purpose, but it is essentially a space which has no width. Cheers Deri
