Translate 0.2pt spacing to internal metrics

Hello, since MS Excel doesn’t support character spacing, a client is requesting an adjusted version of a typeface. Now, the problem is, I am not entirely sure what it means when you adjust the spacing by “0.2pt”. How do I translate this to a value to adjust the metrics in Glyphs? Is this something like 20% of the Em box? So, if I have a UPM of 1000, that would mean +100 units on LSB and RSB, respectively. Is this correct? Just sounds (and looks) like a lot to me.

I think pt as used by your client is an absolute unit. So, they set text with a font size of, say, 10pt. Then 10pt would be 100% of an em and 0.2pt would be 2% of an em.

Ask your client to write a long line of text with it twice, once with the setting and once without, and take a screenshot of it. Then measure the difference of the lines, and divide it by the number of characters.

Oh god, that’s annoying. But it makes sense. Thank you!

Problem is, to be precise, it’s a client of a client, so communication is a bit schleppend. I’ll see.