This case-sensitive code system http://hl7.org/fhir/hl7-work-group defines the following codes:

Code	Display	Definition
cbcc	Community Based Collaborative Care	Community Based Collaborative Care (http://www.hl7.org/Special/committees/cbcc/index.cfm).
cds	Clinical Decision Support	Clinical Decision Support (http://www.hl7.org/Special/committees/dss/index.cfm).
cqi	Clinical Quality Information	Clinical Quality Information (http://www.hl7.org/Special/committees/cqi/index.cfm).
cg	Clinical Genomics	Clinical Genomics (http://www.hl7.org/Special/committees/clingenomics/index.cfm).
dev	Health Care Devices	Health Care Devices (http://www.hl7.org/Special/committees/healthcaredevices/index.cfm).
ehr	Electronic Health Records	Electronic Health Records (http://www.hl7.org/special/committees/ehr/index.cfm).
fhir	FHIR Infrastructure	FHIR Infrastructure (http://www.hl7.org/Special/committees/fiwg/index.cfm).
fm	Financial Management	Financial Management (http://www.hl7.org/Special/committees/fm/index.cfm).
hsi	Health Standards Integration	Health Standards Integration (http://www.hl7.org/Special/committees/hsi/index.cfm).
ii	Imaging Integration	Imaging Integration (http://www.hl7.org/Special/committees/imagemgt/index.cfm).
inm	Infrastructure And Messaging	Infrastructure And Messaging (http://www.hl7.org/special/committees/inm/index.cfm).
its	Implementable Technology Specifications	Implementable Technology Specifications (http://www.hl7.org/special/committees/xml/index.cfm).
mnm	Modeling and Methodology	Modeling and Methodology (http://www.hl7.org/Special/committees/mnm/index.cfm).
oo	Orders and Observations	Orders and Observations (http://www.hl7.org/Special/committees/orders/index.cfm).
pa	Patient Administration	Patient Administration (http://www.hl7.org/Special/committees/pafm/index.cfm).
pc	Patient Care	Patient Care (http://www.hl7.org/Special/committees/patientcare/index.cfm).
pher	Public Health and Emergency Response	Public Health and Emergency Response (http://www.hl7.org/Special/committees/pher/index.cfm).
phx	Pharmacy	Pharmacy (http://www.hl7.org/Special/committees/medication/index.cfm).
brr	Biomedical Research and Regulation	Biomedical Research and Regulation (http://www.hl7.org/Special/committees/rcrim/index.cfm).
sd	Structured Documents	Structured Documents (http://www.hl7.org/Special/committees/structure/index.cfm).
sec	Security	Security (http://www.hl7.org/Special/committees/secure/index.cfm).
us	US Realm Taskforce	US Realm Taskforce (http://www.hl7.org/Special/committees/usrealm/index.cfm).
vocab	Vocabulary	Vocabulary (http://www.hl7.org/Special/committees/Vocab/index.cfm).
aid	Application Implementation and Design	Application Implementation and Design (http://www.hl7.org/Special/committees/java/index.cfm).