See the quote in this answer:
https://mathematica.stackexchange.com/a/171237/5478
and maybe you can find something useful in https://mathematica.stackexchange.com/search?q=stylehints
It can be seen in the Option Inspector: Formatting Options->PrivateFontOptions, for example.
What is the context for this, that is, where is "StyleHints" used?
"StyleHints"
