MORX-18: Contextual Glyph Substitution

The font for this test case has an AAT Extended Glyph Metamorphosis Table with a single Contextual Glyph Substitution Subtable. Its finite-state machine contains a single state with the following transitions:

For glyph B, the transition carries the SetMark flag.
For glyph D, the transition sets MarkIndex to 0, and CurrentIndex to 1.

The glyph substitution table has two entries. Index 0 replaces letters A to E by circled black-on-white forms; index 1 replaces A to E by circled white-on-black forms.

If your rendering system correctly implements Apple Advanced Typography, the renderings should look as expected.

Expected
Observed
Conformance