a. a real hyphen which is an allowed breakpoint, as in much­needed
and as opposed to a non-breaking one like X-Windows (where you
don't want an X- at the end of a line;
b. a virtual hyphen like TeX's \- which marks a valid hyphenation
point like hyphen­ation but which disappears if the word does
not need breaking.
It occurs to me that if we provide an "allowed breakpoint" mark, we
ought also provide a "forbidden breakpoint". ISONUM has both "hyphen"
and "shy" but it's not clear if "hyphen" is just a "-" or if it has
some connotation of permission or forbidding. ISOPUB has "dash" but
calls it a "true graphic" which doesn't tell us much (especially since
ndash and mdash are defined separately).
While browsers display ragged-right setting, there's no need for
hyphenation unless people have really really long words (quite
possible in science work), but if anyone is going to implement
justified setting, they're going to have to use something like Liang's
algorithms (as in PATGEN)...or are we going to see abortions like
variable inter-letter spacing?
///Pe­ter