I've recently been learning more about the OS/2 fsSelection useTypoMetrics flag and was wondering how commonly type designers set that flag in your fonts. Do you set it in your fonts? Or purposefully not?
For those unfamiliar, the useTypoMetrics flag indicates to DirectWrite to use the sTypo metrics values instead of the usWin metrics values for display of fonts.
More info here:
https://www.microsoft.com/typography/otspec/os2.htm#fssThanks!
Comments
If a design doesn't actually require different sTypo and usWin metrics, then we don't set that bit.
The problem is with different versions of Word — in the newer versions, it seems to have started to respect this bit, so documents may have different line spacing. Turning off this bit seems to solve this.
To be honest, it shouldn't make a difference in line spacing, as the way things are set in the fonts are to have the hhea ascent, descent, and line gap values sum to the typo ascent, descent, and line gap values — but it does. I think I'm going to chalk up the visual difference to the fact that the typo values, by virtue of having line space set to a value that isn't 0, means that visually the font shifts up, though it's possible something else is going on.
Older versions of Word display and print using the usWin ascender/descender values.
But in Word 2016, text is displayed using the sTypo ascender/descender/lineGap, but then printed using usWin.
I was hoping that it was a simple error on the part of a programmer (used sTypo when they should have used usWin), but it's been a few months and we haven't seen any updates.
From MS: