The special characters token for a discretionary hyphen is
&:h
The discretionary hyphen is useful to ensure that certain words are hyphenated the way you want, but only if they are at the end of a line (otherwise the discretionary hyphen is invisible, even QuarkXPress's search and replace ignores it).
Another, lesser know, feature of discretionary hyphens is that if you place them immediately before a word, that word will never be hyphenated. This makes sense if one thinks of the discretionary hyphen as a way to split a word into 2 un-hyphenable parts; placing a discretionary hyphen at the beginning of the word means that the part of the word to the right of the hyphen (the entire word in this case) will not be hyphenated.
Topic 175595, last updated on 13-Dec-2022