I'm new to OP and APIs in general - trying to use the API to search and match to a specific project's Subject, but the API documentation doesn't mention how to do this. For example using filters; "filters=[{"subject":{"operator":"=","values":"test"}}]" reports that "InvalidQuery","message":"Subject Operator is not set to one of the allowed values.", meaning the '=' sign, surprisingly, isn't a valid operator.  By chance I noticed elsewhere buried in the docs in an unrelated section that "~" worked as an operator, but this appears to be a "contains the value" and in the above example would return all results with 'test' anywhere in the Subject- certainly closer, but not a match. 

Does anyone know where there is a list of Subject operators that can be used in filters? Or any operators used in filters in any documentation?