Allowed metadata are only ones detailed on the TF DSUB Supp,  3.52.5.2.1 : XDSDocumentEntryClassCode, XDSDocumentEntryPracticeSettingCode, XDSDocumentEntryHealthcareFacilityTypeCode, XDSDocumentEntryEventCodeList, XDSDocumentEntryConfidentialityCode, XDSDocumentEntryAuthorPerson, XDSDocumentEntryFormatCode, XDSDocumentEntryPatientId. Other parameters have no clear applicability as a filter expression (IHE DSUB Supp, 3.52.5.2.1)