A rule class defines the behavior of its rule object instances.
A rule class specifies its name (which must be unique amongst the rule classes in the rule set) and whether it is abstract, and contains:
Optionally, a block of attributes which must have their values specified whenever a rule object instance of the class is created; and
Zero or more calculated Attribute statements, each describing a value that the rule class can calculate.
A rule class may be defined in its own XML file (i.e. where the root XML element is Class) and included into a parent rule set using an Include Statement statement.