Optional filter expression.

Supports JSON and RQL formats:

• JSON: {"and":[{"field":"status","op":"eq","value":"Active"},{"field":"name","op":"ct","value":"Smith, John"}]}
• RQL: and(eq(status,Active),ct(name,Smith%2C%20John)) — values are URL-decoded; encode reserved characters

Operators:
and, or, not (logical); eq, neq, ct, nct, sw, nsw, ew, new, gt, gte, lt, lte (predicate)

Fields (names are matched case-insensitively):
displayName, geography, isPhysical, name, regionalDisplayName, regionCategory

Sort expression for ordering results.

Format:
field:direction,otherField:direction

Directions: asc, desc, ascending, descending — defaults to ascending when omitted

Fields (names are matched case-insensitively):
displayName, geography, isPhysical, name, regionalDisplayName, regionCategory

Default when omitted: displayName:asc.