Fonts have consistent underline thickness?
Dave C Lemon (Adobe Type Team) recommends setting the underline thickness to be consistent across the family.
If thicknesses are not family consistent, words set on the same line which have different styles look strange.
Font has correct post table version?
Apple recommends against using ‘post’ table format 3 under most circumstances, as it can create problems with some printer drivers and PDF documents. The savings in disk space usually does not justify the potential loss in functionality. Source: https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6post.html
The CFF2 table does not contain glyph names, so variable OTFs should be allowed to use post table version 2.
This check expects: - Version 2 for TTF or OTF CFF2 Variable fonts - Version 3 for OTF