These codes are part of the Medicare billing structure for hospice services, which are usually handled via software and downloaded as data files (such as .xml or CSV) to comply with CMS (Centers for Medicare & Medicaid Services) standards.
Revenue codes 651 and 652 (Continuous Home Care) use the Core Based Statistical Area (CBSA) of the beneficiary's residence for payment adjustments. Download 651 655 zip
Hospice claims usually require a two-digit facility code (e.g., "81" for non-hospital based) and a frequency code. These codes are part of the Medicare billing