Final answer:
Nursing Facility Service codes classify medical services for billing purposes and differ for new and established patients, which is determined by prior visits to the physician or their practice within a three-year period.
Step-by-step explanation:
The question pertains to the Nursing Facility Service codes, which are used to categorize medical services provided to patients in a nursing facility. These codes are important for billing and insurance purposes and are divided between new and established patients. A new patient is defined as someone who has not received any professional services from the physician or another physician of the exact same specialty and subspecialty within the same group practice within the past three years. An established patient, on the other hand, has received such services within the past three years. Understanding these codes is crucial for the appropriate billing of medical services provided.