This code system http://hl7.org/fhir/subscription-payload-content defines the following codes:

CodeDisplayDefinition
empty EmptyNo resource content is transacted in the notification payload.
id-only Id-onlyOnly the resource id is transacted in the notification payload.
full-resource Full-resourceThe entire resource is transacted in the notification payload.
<status value="active"/><experimental value="false"/><date value="2021-01-05T10:01:24+11:00"/><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><description value="Codes to represent how much resource content to send in the notification payload."/><jurisdiction><coding><system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/><code value="001"/><display value="World"/></coding></jurisdiction><caseSensitive value="true"/><valueSet value="http://hl7.org/fhir/ValueSet/subscription-payload-content"/><content value="complete"/><concept><code value="empty"/><display value="Empty"/><definition value="No resource content is transacted in the notification payload."/></concept><concept><code value="id-only"/><display value="Id-only"/><definition value="Only the resource id is transacted in the notification payload."/></concept><concept><code value="full-resource"/><display value="Full-resource"/><definition value="The entire resource is transacted in the notification payload."/></concept></CodeSystem>