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9.2 Pattern Attributes

The attribute field in the `:' line of a pattern consists of a sequence of zero or more of the following characters, each with a different meaning. The attributes may be roughly classified as constraints, which determine whether or not the pattern is matched, and actions, which describe what is to be done when the pattern is matched, typically to add a move reason.

9.2.1 Constraint Pattern Attributes

9.2.2 Action Attributes

A commonly used class is OX (which rejects pattern if either side has dead stones). The string `-' may be used as a placeholder. (In fact any characters other than the above and `,' are ignored.)

The types `o' and `O' could conceivably appear in a class, meaning it applies only to UNKNOWN. `X' and `x' could similarly be used together. All classes can be combined arbitrarily.