How does Font Book.app determine the "Design style" for a Smart Collection?

In Font Book.app one of the criteria for creating a Smart Collection is "Design style".

Font Book.app Smart Collection dialog

How does Font Book.app determine whether or not a given font falls into one of the available categories?


Solution 1:

OK, I think I figured it out... Opening a font in RoboFont, I scoured all the obscure meta-info available and finally found the entry that seems to correspond to what FontBook uses for the Design Style in the section called Panose (a term I had never heard of!). Long story short... FontBook seems to probably use the Proportion to determine the style. 😜

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