This code system http://terminology.hl7.org/CodeSystem/can-push-updates defines the following codes:

CodeDisplay
yes Yes
no No
undetermined Undetermined
 <status value="draft"/> <experimental value="false"/> <date value="2018-06-05T14:06:02+00:00"/> <publisher value="HL7 (FHIR Project)"/> <contact> <telecom> <system value="url"/> <value value="http://hl7.org/fhir"/> </telecom> <telecom> <system value="email"/> <value value="fhir@lists.hl7.org"/> </telecom> </contact> <contact> <telecom> <system value="url"/> <value value="http://hl7.org/fhir"/> </telecom> <telecom> <system value="email"/> <value value="fhir@lists.hl7.org"/> </telecom> </contact> <description value="Ability of the primary source to push updates/alerts"/> <caseSensitive value="true"/> <valueSet value="http://terminology.hl7.org/ValueSet/verificationresult-can-push-updates"/> <content value="complete"/> <concept> <code value="yes"/> <display value="Yes"/> </concept> <concept> <code value="no"/> <display value="No"/> </concept> <concept> <code value="undetermined"/> <display value="Undetermined"/> </concept> </CodeSystem>