These compatibility rules are based on a compatibility operator and
the value of two expressions, a left and a right expression. The compatibility
operator (which can be incompatible, co-dependent, or requires) decides
how the two expressions are interpreted relative to each other. The left
and right expressions can be any valid boolean expression (with and,
or, not, [,],) that includes feature/option pairs as the operands.
In the boolean expression, the feature/option pair is enclosed in
double quotes.
