### MORX-22: Contextual Glyph Substitution with MarkIndex and CurrentIndex

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 two states (0 and 1) with the following transitions:

- For glyph A:

- In state 0, the machine moves to state 1 using a transition that carries both the SetMark and DontAdvance flags.
- In state 1, the machine moves back to state 0 using a transition that executes glyph substitution #0 on the marked glyph, and also glyph substitution #1 on the current glyph.

The input string for this test is A. If your rendering system implements Apple Advanced Typography, both MarkIndex and CurrentIndex will affect the same glyph. If your implementation is correct, it should first execute the glyph substitution for MarkIndex to replace A by B. Then, it should execute the glyph substitution for CurrentIndex, which replaces B (the result of the previous substitution) by C. Therefore, the final result should be C.

| A
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| Expected |
Observed |
Conformance |