and indicates an evaluation to TRUE if all the predicates evaluate to TRUE.
or indicates an evaluation to TRUE if one of the predicates evaluates to TRUE.
xor indicates an evaluation to TRUE if an odd number of the predicates evaluates to TRUE and all others evaluate
to FALSE.
surrogate allows for specifying surrogate predicates. They are used for cases where a missing value appears in
the evaluation of the parent predicate such that an alternative predicate is available.
