Basic Latin: Significance of NULL and CR?

[madig]

Why are these required? And what properties (contents, spacing, ...) should they have?

[arrowtype]

Should these / can these be removed? It seems to be the consensus opinion...

https://github.com/googlefonts/glyphsets/issues/21

[anthrotype]

they are not required, they are legacy TrueType recommendations and serve no purpose.

The "First Four Glyphs" section of the OT spec was removed since OT 1.8 (2016) (see changelog)

[bobh0303]

IMO, yes they should be removed. Currently, if CR (aka nonmarkingreturn) and/or NULL (aka .null) are included then one of two things happens:

1. If the are unencoded, then fontbakery's unreachable_glyphs check complains about them.
2. If the are encoded, then fontbakery doesn't complain but the OS2.usFirstCharIndex will have to be set below 0x0020 which (a) goes against the OpenType recommendations and (b) has been known to cause problems — at least in the past — with some software.

Can we just do this? If we are concerned about risk of some latent bug, then we should change the unreachable_glyphs check so it doesn't complain.

[bobh0303]

According to https://github.com/fonttools/fontbakery/issues/938#issuecomment-597593292 and https://github.com/MicrosoftDocs/typography-issues/issues/346#issuecomment-688531945 there is some relatively recent software that expects glyph 1 to be empty (and presumably width-less), though the most recent such are only in COLR fonts.

Thus I change my opinion:

• We should not be recommending anything between .notdef and space except in COLR fonts in which case NULL/.null is recommended.
• The NULL/.null glyph, if present, should be empty and width-less.
• Neither of these glyphs should be encoded, and the resulting OS2.firstCharIndex should be 0x0020.
• There should be no other glyphs between these first one or two and U+0020 space, in particular no CR/nonmarkingreturn, tab, etc.

I intentionally did not say that NULL/.null may not be in non-COLR fonts — but others may want to challenge that idea.

[yanone]

Since you're discussing Fontbakery checks, I think it's a good idea to move the conversation over there, as it would also have more eyes look over it, and then have the tooling such as glyphsets follow whichever outcome is accepted there. Fontbakery is kind of the central source of truth.