Would it be possible to drop `standout` (as it's rather ambiguous) and instead add both `italic` and `reverse`? They both have `terminfo` entries.
If you're referring to Functions/Misc/colors, that's what my proposed patch already does.
If you're referring to prompts, "standout" appears only in the documentation, but the prompt sequences are %S (on) and %s (off) to be suggestive thereof. %R and %I are already in use for other features; we'd need some kind of extended syntax (%F{name} is not nestable).