[tex-k] ligatures and explicit kerns

[Stephan Hennig]

Karl, Julian,

thank you both for your answers!

Am 03.10.2014 um 01:48 schrieb Karl Berry:
> 
>     ligatures won't be inserted in words that do contain explicit kerns.
>     ...
>     shelf\/fulfi
> 
> It would be unexpected, at least by me, for a kern in one position
> within a word to disable ligatures everywhere within the word, not just
> at the point of the kern.  I agree that the text you quoted can be read
> that way; repeating it here:
> 
>   Appendix H points out that ligatures are put into a hyphenated
>   word that contains no ``explicit kerns,'' and an italic correction
>   is an explicit kern.
> 
> but I would suggest interpreting it as a more limited statement:
> ligatures are avoided at the point of the explicit kern.  (After all, TB
> is not intended to be a legal document.)

Hm, that sounds a bit like cheating. :-)


> At most there might be a clearer statement in TB, if you want to make
> a report for DEK's consideration;

I'll think about that.  (There must be something else DEK had in mind
when writing the answer.)  Do the increasing update cycles for TeX and
MF also apply to DEK's books, i.e., will he care to look at book error
reports before 2020?


> obviously the actual behavior is not going to be changed.

Sure. :-)


>     I didn't find the place in appendix H the quote refers to, so
>     pointers would be appreciated.
> 
> I do not see a single "place" that is being referred to; as far as I can
> tell, it's rather a consequence of all the multifarious rules in App. H.
> (But maybe I'm missing it, I did not reread every word [again].)

:-)  Will reread appendix H thoroughly before reporting it as an error.


> Perhaps the most direct statement is this one, talking about what
> "hyphenating a word" actually means (namely, inserting discretionaries):
> 
>   \ddanger Trial words ...
>   If other hyphenation points are found, one or more discretionary items
>   are inserted in the word; ligatures and implicit kerns are reconstituted
>   at the same time.
> 
> The first statement is a negative construction, the second a positive
> one.  Always tricky to compare.

True.  But I still have the feeling that the wording in the answer
should be changed.

Best regards,
Stephan Hennig