This code system http://terminology.hl7.org/CodeSystem/observation-category defines the following codes:

Code	Display	Definition
social-history	Social History	Social History Observations define the patient's occupational, personal (e.g., lifestyle), social, familial, and environmental history and health risk factors that may impact the patient's health.
vital-signs	Vital Signs	Clinical observations measure the body's basic functions such as blood pressure, heart rate, respiratory rate, height, weight, body mass index, head circumference, pulse oximetry, temperature, and body surface area.
imaging	Imaging	Observations generated by imaging. The scope includes observations regarding plain x-ray, ultrasound, CT, MRI, angiography, echocardiography, and nuclear medicine.
laboratory	Laboratory	The results of observations generated by laboratories. Laboratory results are typically generated by laboratories providing analytic services in areas such as chemistry, hematology, serology, histology, cytology, anatomic pathology (including digital pathology), microbiology, and/or virology. These observations are based on analysis of specimens obtained from the patient and submitted to the laboratory.
procedure	Procedure	Observations generated by other procedures. This category includes observations resulting from interventional and non-interventional procedures excluding laboratory and imaging (e.g., cardiology catheterization, endoscopy, electrodiagnostics, etc.). Procedure results are typically generated by a clinician to provide more granular information about component observations made during a procedure. An example would be when a gastroenterologist reports the size of a polyp observed during a colonoscopy.
survey	Survey	Assessment tool/survey instrument observations (e.g., Apgar Scores, Montreal Cognitive Assessment (MoCA)).
exam	Exam	Observations generated by physical exam findings including direct observations made by a clinician and use of simple instruments and the result of simple maneuvers performed directly on the patient's body.
therapy	Therapy	Observations generated by non-interventional treatment protocols (e.g. occupational, physical, radiation, nutritional and medication therapy)
activity	Activity	Observations that measure or record any bodily activity that enhances or maintains physical fitness and overall health and wellness. Not under direct supervision of practitioner such as a physical therapist. (e.g., laps swum, steps, sleep data)