This code system http://hl7.org/fhir/practitioner-role defines the following codes:

CodeDisplayDefinition
doctorDoctorA qualified/registered medical practitioner
nurseNurseA practitoner with nursing experience that may be qualified/registered
pharmacistPharmacistA qualified/registered/licensed pharmacist
researcherResearcherA practitioner that may perform research
teacherTeacher/educatorSomeone who is able to provide educational services
ictICT professionalSomeone who is qualified in Information and Communication Technologies