Re: Zero Width Space (was Re: How to print a literal '.' as the first character in a line?)

[Deri]

On Saturday, 4 June 2022 22:44:10 BST Dave Kemper wrote:
> On 6/4/22, James K. Lowden <jklowden@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