This code system http://hl7.org/fhir/report-participant-type defines the following codes:

CodeDisplayDefinition
test-engine Test EngineThe test execution engine.
client ClientA FHIR Client.
server ServerA FHIR Server.
<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="The type of participant."/><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/report-participant-type"/><content value="complete"/><concept><code value="test-engine"/><display value="Test Engine"/><definition value="The test execution engine."/></concept><concept><code value="client"/><display value="Client"/><definition value="A FHIR Client."/></concept><concept><code value="server"/><display value="Server"/><definition value="A FHIR Server."/></concept></CodeSystem>