Unable to add "linkedValue" with otlLib.builder buildStatTable()

Scenario:

• I have a variable font
• I am adding a STAT table with this add-STAT.py script
• My script includes this entry for the Regular weight: dict(nominalValue=400, rangeMinValue=350.00001, rangeMaxValue=450, name="Regular", flags=0x2, linkedValue=700)
• When I use ttx -t STAT -o- "fontfamily.ttf" to view the result, there is most of the stat table, but the Regular entry has no <LinkedValue> entry
• FontBakery is telling that 700 is an expected and missing linked value for Regular

I’ve triple-checked my syntax and spelling and I think I’m doing everything correctly, though of course I might be missing something.

I’m on FontTools version 4.37.1, though a test of the same process on 4.35.0 yields the same result (not surprising, as I think this function has been stable or awhile). I have also tested dropping the table (ttx -x), checking that is was gone, then re-running the script… and got the same result.

Could something be getting in the way of adding this value? Is FontBakery incorrect in saying that Regular should have a linkedValue of 700?

Thank you so much for any insights here!

[anthrotype]

Ditto what Jany says. Maybe buildStatTable should raise an error explaining this when both a range and a linkedValue is requested.

[belluzj]

I think it’s because there is no STAT format for your Regular entry, that has both a range and a linked value, it’s either format 2 for the range or format 3 for the linkedValue.

There’s a little recap table in the designspace docs: https://fonttools.readthedocs.io/en/latest/designspaceLib/xml.html#label-element-axis

OT Spec: https://docs.microsoft.com/en-us/typography/opentype/spec/stat#axis-value-table-format-1