Ordinals OpenType feature error

[Dan]

I get another OpenType feature error message: "Ordinals:Invalid use of Glyph Group in Ligature Substitution".

My Ordinals feature is:
languagesystem DFLT dflt;

languagesystem latn dflt;

@numbrs = [
zero.slashed zero one two three four five six seven eight nine zero.tab one.tab two.tab three.tab four.tab five.tab six.tab seven.tab eight.tab nine.tab
];

feature ordn {

sub @numbrs a' by ordfeminine;
sub @numbrs A' by ordfeminine;
sub @numbrs o' by ordmasculine;
sub @numbrs O' by ordmasculine;

} ordn;

What is my mistake?

[Allan Murray]

What you are trying to implement there is a contextual substitution. Type 3.2 does not currently support contextual substitution, and thinks you are trying to do a ligature substution with a glyph group, which is not allowed.

If you look at page 44 in the manual (Lookup types), the table indicates which types of lookup are currently supported, and how you can use glyph groups for the different lookup types.

[Dan]

Will this contextual substitution support into the future program updates?

[Allan Murray]

Yes, it is planned for an update within the next few months.

[Dan]

Ok. Great!

[Allan Murray]

Contextual lookups are now supported (Windows version 3.2.042, and soon Mac):
forum.cr8software.net/thread/319/type-3-2-update

[Dan]

Good news! Allan, thanks for the update.