[Jellby]

Originally Posted by Psymon

Not all of the ligatures get changed "automatically" -- only some seem to

Let me guess... ff, fi, ffi, fl, ffl are changed automatically.

Those are the "standard ligatures", the ones more often defined, and activated with the "liga" feature, which is on by default (if the reader supports it). The others (ct in this case) are in a different set called "discretionary ligatures", and are disabled by default, you need to activate the "dlig" feature.

but perhaps more importantly is the long-ess (which I need to make use of more than the regular "s").

Depending on how picky you are, you could choose one of two routes:

1. Actually write the long-s character (U+017F: ſ) in your input where you need it. That should work and give you most of its accompanying ligatures, which are in the "liga" table (except ſ+s = ß, which is in "dlig"). The problem with this is that it breaks searching, but you get more control

2. Activate the "hist" feature, intended for getting historical variants of some letters (only the long-s in our case). This should replace every "s" character in the input with a "ſ" (but only when it is followed by some lowercase letter). This is done on the fly and it's transparent to searching and copy-paste (or should be), but then you are at the mercy of the replacement rules programmed in the font, and of course you need to be able to activate the "hist" feature. Since the fonts are open-licensed, you could program more elaborate replacement rules for the long-s if you are not satisfied with the provided one.

So for all those long-esses, and for any ligs I want to use, it would seem that I still have to manually put all those in individually

Only if your reader does not support enabling the OpenType features above, and only if you prefer having unsearchable and hard to maintain text, rather than text that will not be "perfect" in less capable readers, but still readable and enjoyable (and the spelling still looks "olde" without all these ligatures and long-s), and will remain "perfect" in the better readers.

so doesn't that leave me back to square one, in the same boat as I am with the JSL fonts?

If you cannot get your reader to automatically use the ligatures... yes, almost. Except that you'd be using characters with no other predefined meaning, and without the font you'll see something like "o?en" (with the ? in a black lozenge, or an empty rectangle) instead of "o¤en", and you'd be complying with the ePub spec

All the various ligatures are either in a "Private Use Area" or "Alphabetic Presentation Forms" part of the font -- is that normal, and "correct" (as per earlier discussions here)?

Yes, exactly. The latter are the defined ligatures in the Unicode standard, and the "liga" table, the former is an area used for whatever you want... and these "discretionary ligatures" are a common denizen there.