ABN stands for Advanced Beneficiary Notification. An ABN must be signed prior to providing a Medicare service or test to document that the patient is willing to assume responsibility for payment of services that Medicare may not cover when subject to either National or Local Coverage Determinations (NCD) or (LCD).
Chinchillas are crepuscular (most active around dawn and dusk) rodents, slightly larger and more robust than ground squirrels. They are native to the Andes mountains in South America and live in colonies called  herds  at high elevations up to 4,270 m (14,000 ft).
The name Chowchilla is derived from the Native American tribe of Chauchila (the spelling is inconsistent in reference guides) Yokut Indians which once lived in the area. The name itself evidently translates as Murderers and is apparently a reference to the warlike nature of the Chauchila tribe.