I'm looking for some confirmation of the types of fields that are or are not able to be queried using the REST API. From what I've seen, most read-only fields can't be queried. Some, such as custom multi-select fields, which are read-only, can query for all allowed values except for the null value. Custom multi-select fields which are not read-only are able to query all values, including null. The query looks like this: query=(c_CustomMultiSelect%20contains%20%22null%22). This query works for the non read-only field, but not for the read-only field. Getting the attributes for the read-only custom multi-select field, it has valid AllowedQueryOperators and null is one of the AllowedValues. There are a number of other fields which seem to not support querying through the REST API, and they appear to be read-only, though there are also some read-only fields which do support queries. Is there a field attribute that I'm missing or some other way of determining whether a field is able to be queried or not?