The service implements OGC Filter Encoding 2.0 Encoding Standard.
Service supports following logical operators: AND, OR, NOT.
The service supports following spatial operators: Within, DWithin, BBox.
Service supports following Comparison Operators: PropertyIsEqualTo-Operator, PropertyIsNotEqualTo-Operator, PropertyIsLessThan-Operator, PropertyIsGreaterThan-Operator, PropertyIsLessThanOrEqualTo-Operator, PropertyIsGreaterThanOrEqualTo-Operator, PropertyIsNull-Operator, PropertyIsNil-Operator, ContainsProperty-Operator.
Service supports following Reference Operators: References, ReferencedBy.
Reference
OGC Filter Encoding 2.0 Encoding Standard
https://www.ogc.org/standards/filter/