We have a bunch of fonts with a slant axis coming up (with slant, backslant, italic), I think we need to set up some kind of a standard to handle it properly even though GF won't serve it before a while. Nothing prevent from integrating it correctly into the STAT table and therefore the new config.yaml.

• What fallback names? Right now axis registry has "0=Default". After discussing with @arrowtype, @vv-monsalve and @tphinney, "Upright/Oblique" seem appropriate for our projects. Although, doesn't give an answer for a BackSlant fallback.
• Range values accepted? It would make sense.
• Linked value flag between Upright and Oblique when no ital axis?
• Do we tick the "is italic" flag in Glyphs when no ital axis?
• Axis Order ? I remember we said Oblique at the end, like Italic. So slant axis should be after weight. But then there is the Backslant which should go on the family name side…
• We should be able to give an examples for these 3 cases (STAT, Static Instances scheme) :
  -- only slant (with Oblique fallback)
  -- only slant (with Oblique and Backslant fallbacks)
  -- slant + ital (use of STAT format 4?)

References from @arrowtype:

• VF Slant Browser support
• VF Slant Browser support updated
• Recursive STAT builder by @benkiel