This code system https://bluebutton.cms.gov/assets/ig/CodeSystem-betos-cd defines the following codes:
| Code | Display | Definition |
| M1A | Office visits - new | Office visits - new |
| M1B | Office visits - established | Office visits - established |
| M2A | Hospital visit - initial | Hospital visit - initial |
| M2B | Hospital visit - subsequent | Hospital visit - subsequent |
| M2C | Hospital visit - critical care | Hospital visit - critical care |
| M3 | Emergency room visit | Emergency room visit |
| M4A | Home visit | Home visit |
| M4B | Nursing home visit | Nursing home visit |
| M5A | Specialist - pathology | Specialist - pathology |
| M5B | Specialist - psychiatry | Specialist - psychiatry |
| M5C | Specialist - ophthalmology | Specialist - ophthalmology |
| M5D | Specialist - other | Specialist - other |
| M6 | Consultations | Consultations |
| P0 | Anesthesia | Anesthesia |
| P1A | Major procedure - breast | Major procedure - breast |
| P1B | Major procedure - colectomy | Major procedure - colectomy |
| P1C | Major procedure - cholecystectomy | Major procedure - cholecystectomy |
| P1D | Major procedure - turp | Major procedure - turp |
| P1E | Major procedure - hysterectomy | Major procedure - hysterectomy |
| P1F | Major procedure - explor/decompr/excisdisc | Major procedure - explor/decompr/excisdisc |
| P1G | Major procedure - Other | Major procedure - Other |
| P2A | Major procedure, cardiovascular-CABG | Major procedure, cardiovascular-CABG |
| P2B | Major procedure, cardiovascular-Aneurysm repair | Major procedure, cardiovascular-Aneurysm repair |
| P2C | Major Procedure, cardiovascular-Thromboendarterectomy | Major Procedure, cardiovascular-Thromboendarterectomy |
| P2D | Major procedure, cardiovascualr-Coronary angioplasty (PTCA) | Major procedure, cardiovascualr-Coronary angioplasty (PTCA) |
| P2E | Major procedure, cardiovascular-Pacemaker insertion | Major procedure, cardiovascular-Pacemaker insertion |
| P2F | Major procedure, cardiovascular-Other | Major procedure, cardiovascular-Other |
| P3A | Major procedure, orthopedic - Hip fracture repair | Major procedure, orthopedic - Hip fracture repair |
| P3B | Major procedure, orthopedic - Hip replacement | Major procedure, orthopedic - Hip replacement |
| P3C | Major procedure, orthopedic - Knee replacement | Major procedure, orthopedic - Knee replacement |
| P3D | Major procedure, orthopedic - other | Major procedure, orthopedic - other |
| P4A | Eye procedure - corneal transplant | Eye procedure - corneal transplant |
| P4B | Eye procedure - cataract removal/lens insertion | Eye procedure - cataract removal/lens insertion |
| P4C | Eye procedure - retinal detachment | Eye procedure - retinal detachment |
| P4D | Eye procedure - treatment of retinal lesions | Eye procedure - treatment of retinal lesions |
| P4E | Eye procedure - other | Eye procedure - other |
| P5A | Ambulatory procedures - skin | Ambulatory procedures - skin |
| P5B | Ambulatory procedures - musculoskeletal | Ambulatory procedures - musculoskeletal |
| P5C | Ambulatory procedures - inguinal hernia repair | Ambulatory procedures - inguinal hernia repair |
| P5D | Ambulatory procedures - lithotripsy | Ambulatory procedures - lithotripsy |
| P5E | Ambulatory procedures - other | Ambulatory procedures - other |
| P6A | Minor procedures - skin | Minor procedures - skin |
| P6B | Minor procedures - musculoskeletal | Minor procedures - musculoskeletal |
| P6C | Minor procedures - other (Medicare fee schedule) | Minor procedures - other (Medicare fee schedule) |
| P6D | Minor procedures - other (non-Medicare fee schedule) | Minor procedures - other (non-Medicare fee schedule) |
| P7A | Oncology - radiation therapy | Oncology - radiation therapy |
| P7B | Oncology - other | Oncology - other |
| P8A | Endoscopy - arthroscopy | Endoscopy - arthroscopy |
| P8B | Endoscopy - upper gastrointestinal | Endoscopy - upper gastrointestinal |
| P8C | Endoscopy - sigmoidoscopy | Endoscopy - sigmoidoscopy |
| P8D | Endoscopy - colonoscopy | Endoscopy - colonoscopy |
| P8E | Endoscopy - cystoscopy | Endoscopy - cystoscopy |
| P8F | Endoscopy - bronchoscopy | Endoscopy - bronchoscopy |
| P8G | Endoscopy - laparoscopic cholecystectomy | Endoscopy - laparoscopic cholecystectomy |
| P8H | Endoscopy - laryngoscopy | Endoscopy - laryngoscopy |
| P8I | Endoscopy - other | Endoscopy - other |
| P9A | Dialysis services (Medicare fee schedule) | Dialysis services (Medicare fee schedule) |
| P9B | Dialysis services (non-Medicare fee schedule) | Dialysis services (non-Medicare fee schedule) |
| I1A | Standard imaging - chest | Standard imaging - chest |
| I1B | Standard imaging - musculoskeletal | Standard imaging - musculoskeletal |
| I1C | Standard imaging - breast | Standard imaging - breast |
| I1D | Standard imaging - contrast gastrointestinal | Standard imaging - contrast gastrointestinal |
| I1E | Standard imaging - nuclear medicine | Standard imaging - nuclear medicine |
| I1F | Standard imaging - other | Standard imaging - other |
| I2A | Advanced imaging - CAT/CT/CTA: brain/head/neck | Advanced imaging - CAT/CT/CTA: brain/head/neck |
| I2B | Advanced imaging - CAT/CT/CTA: other | Advanced imaging - CAT/CT/CTA: other |
| I2C | Advanced imaging - MRI/MRA: brain/head/neck | Advanced imaging - MRI/MRA: brain/head/neck |
| I2D | Advanced imaging - MRI/MRA: other | Advanced imaging - MRI/MRA: other |
| I3A | Echography/ultrasonography - eye | Echography/ultrasonography - eye |
| I3B | Echography/ultrasonography - abdomen/pelvis | Echography/ultrasonography - abdomen/pelvis |
| I3C | Echography/ultrasonography - heart | Echography/ultrasonography - heart |
| I3D | Echography/ultrasonography - carotid arteries | Echography/ultrasonography - carotid arteries |
| I3E | Echography/ultrasonography - prostate, transrectal | Echography/ultrasonography - prostate, transrectal |
| I3F | Echography/ultrasonography - other | Echography/ultrasonography - other |
| I4A | Imaging/procedure - heart including cardiac catheterization | Imaging/procedure - heart including cardiac catheterization |
| I4B | Imaging/procedure - other | Imaging/procedure - other |
| T1A | Lab tests - routine venipuncture (non-Medicare fee schedule) | Lab tests - routine venipuncture (non-Medicare fee schedule) |
| T1B | Lab tests - automated general profiles | Lab tests - automated general profiles |
| T1C | Lab tests - urinalysis | Lab tests - urinalysis |
| T1D | Lab tests - blood counts | Lab tests - blood counts |
| T1E | Lab tests - glucose | Lab tests - glucose |
| T1F | Lab tests - bacterial cultures | Lab tests - bacterial cultures |
| T1G | Lab tests - other (Medicare fee schedule) | Lab tests - other (Medicare fee schedule) |
| T1H | Lab tests - other (non-Medicare fee schedule) | Lab tests - other (non-Medicare fee schedule) |
| T2A | Other tests - electrocardiograms | Other tests - electrocardiograms |
| T2B | Other tests - cardiovascular stress tests | Other tests - cardiovascular stress tests |
| T2C | Other tests - EKG monitoring | Other tests - EKG monitoring |
| T2D | Other tests - other | Other tests - other |
| D1A | Medical/surgical supplies | Medical/surgical supplies |
| D1B | Hospital beds | Hospital beds |
| D1C | Oxygen and supplies | Oxygen and supplies |
| D1D | Wheelchairs | Wheelchairs |
| D1E | Other DME | Other DME |
| D1F | Prosthetic/Orthotic devices | Prosthetic/Orthotic devices |
| D1G | Drugs Administered through DME | Drugs Administered through DME |
| O1A | Ambulance | Ambulance |
| O1B | Chiropractic | Chiropractic |
| O1C | Enteral and parenteral | Enteral and parenteral |
| O1D | Chemotherapy | Chemotherapy |
| O1E | Other drugs | Other drugs |
| O1F | Hearing and speech services | Hearing and speech services |
| O1G | Immunizations/Vaccinations | Immunizations/Vaccinations |
| Y1 | Other - Medicare fee schedule | Other - Medicare fee schedule |
| Y2 | Other - non-Medicare fee schedule | Other - non-Medicare fee schedule |
| Z1 | Local codes | Local codes |
| Z2 | Undefined codes | Undefined codes |
