Simple categories matching straightforward:

• project,
• procedure,

Members with property straightforward:

• polypectomy,
• treatment,
• tonsillectomy,
• cataract_operations,
• cholecystectomy,
• abc_classification,
• service,
• blood-pressure_reading,
• hysterectomy,
• dialysis,
• appendicectomy,
• tissue_collection,
• shoulder_arthroscopy,
• knee_surgery,
• sewage_treatment,
• lung_biopsy,