Re: FreeType INSTCTRL behavior (Po Lu) (Re: Freetype-devel Digest, Vol 217, Issue 8)

[Alexei Podtelezhnikov]

> >> >   these new values.
> > You are looking at the outdated Apple's specifications. Please check
> > with OpenType 1.9 instead:
> > https://learn.microsoft.com/en-us/typography/opentype/spec/tt_instructions#instruction-execution-control
> >
> > Specifically, "INSTCTRL[ ] can only be executed in the CVT program."
> > There are further clarifications
> > https://learn.microsoft.com/en-us/typography/cleartype/truetypecleartype#instctrl
> >
> > Best,
> > Alexei
>
> I don't see anything there that contradicts the behavior of my
> interpreter, though.
>
> The control value program executes _NO_ INSTCTRL[] instructions
> whatsoever, yet the reference points and the freedom vector are reset
> after execution.

How about this: https://learn.microsoft.com/en-us/typography/opentype/spec/prep?
"The Control Value Program consists of a set of TrueType instructions
that will be executed... before each glyph is interpreted."