Well, that's charmingly abstract. Some questions:
- Can X contain P? Or, rather, how can you be sure you've found the right P?
- Do either APB or CXP appear multiple times? I.e. APB APB CXP CXP? If so, how should they be treated?
- Do A?B and C?P appear multiple times with different values? E.g. APB CXP ASB CXS? How should they be treated?
- Can you give some real examples of APB and CXP?
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