What is the name for an alternative dlig?

Glyphs
1

I have a lot of dlig glyphs what is the proper name for each alternative is it

f_f.dlig.001

or
f_f.dlig.alt

Many thanks
Simon

2

Depends how you like to access them. With a stylistic set?

3

If it was via stylistic set would it be

f_f.dlig.ss01, f_f.dlig.ss02

Is f_f.dlig.alt, f_f.dlig.alt1 the proper format?

Cheers
si

4

This. Alternatively, you could also use cvXX (cv01–cv99) instead of ssXX.

Make sure dlig comes before ss01 in Font Info > Features.