Although the eszet is regarded by Germans as a letter, and not a ligature, its form had its origin in a ligature of long s followed by short s which fundamentally resembled the fi and fl ligatures used in English-language typography.
Some orthographies for the German language now allow the sequence sss in German texts.
Well, in English-language typography, the fi and fl ligatures are accompanied by ffi and ffl, and so it would be easy and obvious to design what I might call a "double eszet", starting from a ligature of two long s letters followed by one short s, and then modifying the form to correspond to what the eszet looks like today.
Now this might be as outrageously stupid as some other things I've previously said on this subject... for the primary reason that, while sss can now occur, those three letters s in a row aren't unified, but are happening through two separate syllables following each other, so that unifying all three of those letters into a double eszet would be a very incorrect spelling, as it would mislead people about where the syllables are divided and how the word is to be pronounced and so on.
Comments
But your text is about a new ligature, similar to ffi and ffl. That would be a new and optional glyph, which is an entirely different thing.
You say that the input for the ligature is “sss”. I would think that “sss” should always look different from “ßs” or “sß”—if the ligature for “sss” looks much like one of the other two, that seems like a mistake. You talk about taking the “sss” sequence and giving long-s appearances to some of the s’s. That seems very odd to me.
And also, seeing as it is a ligature… should this ligature be on by default ('liga') or only when actively turned on by an end user ('dlig')?
It might depend partly on the degree of normality of the ligature. What you describe, if I am understanding correctly, seems noticeably odd/unorthodox, so I would go with a discretionary ligature—that is, one that is not on by default.
You should start another topic with this problem.
In order to help you, it should be interesting to know which software you use to create your fonts?
Fontlab, Glyphs, Font Creator, etc. have excellent help and tutorials to achieve this.
hey Yves, thank you for answering. i am indeed looking (and finding) all over the place for info. as a beginner, i sometimes don't know what exactly i am looking for before i found it
i understood my concern (whether ligatures are language-specific) as part of this topic. sorry for that. i will try first to make my few ligatures/alternatives work at all, maybe localising later if this is the standard procedure. i work with fontlab btw; i haven't worked with other font editors not to confuse me more at this stage.
About OpenType features:
Registered features, p-t (OpenType 1.9) - Typography | Microsoft Learn
Putting it Together (opentypecookbook.com)
OpenType features - Help - Typofonderie
You could also try the Fontlab forum. The team and the members are very helpful.
FontLab 8 - FontLab Forum
instalment
fulfil
skilful
And my pet peeve, though not exclusive to Britain: skipping the "s" in the possessive (Chris’ corner)?
fully (full + ly)
There are probably others. So I guess English does this.
Hmmm, soporifically boring in my opinion. Zzz.
Languages evolve towards the practical. (If that's a theory it's probably wrong)... But I can, without much reflection, see why there are no triple ells and esses. Or zeds... Not on topic, but English once had a grammatical system of gendered nouns. Just like other languages. Then the Vikings (... famously lazy language learners) came and killed them all.
But, back to the present topic: I can picture the punch cutters back when standardized spelling was becoming a thing in the industry, upon hearing the proposal to correct the oversight of a lack of triple ell and ess ligatures muttering "Uh... I don't think so." And scribes in their time: "Oh my dear God! I thinkest not, Satan."