The list depends on the factory from which the TDFilter was created. For example, if the filter is created from a TestFactory, the field list will consist of the names of the Test fields: TS_ATTACHMENT, TS_CREATION_DATE, TS_DESCRIPTION, TS_RESPONSIBLE, TS_STATUS, TS_SUBJECT, TS_TEMPLATE, TS_TEST_ID, TS_NAME, and so on.