Whether Field Can Be Used in WHERE Clause

Constant	Possibility to use a field in a WHERE clause
gdbExtDBSearchableUnsearchable	Impossible to use in a WHERE clause.
gdbExtDBSearchableLikeOnly	Possible to use in a LIKE predicate only.
gdbExtDBSearchableAllExceptLike	Possible to use in all predicates except a LIKE predicate.
gdbExtDBSearchableSearchable	Possible to use in all predicates.