@w__h_ Yea they can definitely be less than the UPM but it is a pain in the ass when its greater because you'll have to compensate with your line gap values if you keep it 1000. no fun

@connordavenpo I think from Google fonts testing.. it’s ok to go more no? Like especially for Indic or Vietnamese

@w__h_ It’s not a bad rule of thumb for Latin text faces. I had a client call to ask what was up with the rendering in a particular piece of software, and setting ascender and descender values to span the UPM was what fixed it.

@nondescriptes Which values though hhea, os2 or typo? I think the above is referring to the design app values which I don’t think have any bearing on the calculated metrics table values either

@w__h_ I certainly dont do it that way :/

@w__h_ I don't think this is the first time the type community has questioned this guy

@w__h_ According to Glyphs App, this used to be a requirement and was given up a couple of years ago, also because scripts of various languages wouldn’t support it.

@w__h_ I think it’s also a holdover piece of advice that was supposed to make OS/2 + hhea tables easier to manage ? I think there was also at some point in time the possibility for clipping

@w__h_ For the first line in a text “frame”, some typesetting engines used Ascender, but at least one Adobe engine used UPM–Descender. So the A+D=UPM rule was helpful to maintain consistency.

@w__h_ @JillPichotta i remember you recommending this…care to chime in?

@w__h_ They don’t, but it’s a good reference