Automatic name shortening e.g. Ultra -> Ul

Hi all,

I’ve noticed that Glyphs 3 automatically shortens the name ID1 by replacing certain terms by prefixes if the family name exceeds a certain length. What is the rationale/what are the exact rules for doing this? I am asking because:

  1. The resulting names are still longer than 29 characters, which is the limit specified in the instance tutorial
  2. There are still other, unshortened terms (e.g. Ultra Bold → Ul Bold and not UlBd)
  3. The shortening doesn’t take place consistently across the whole family. So Ultra Bold Italic may be shortened to Ul Bold Italic but Ultra Bold remains unshortened as it’s shorter anyway.