The International Chiropractor's Association (ICA) states that the "chiropractic spinal adjustment is unique and singular to the chiropractic profession", and that it "is characterized by a specific thrust applied to the vertebra utilizing parts of the vertebra and contiguous structures as levers to directionally correct articular malposition. Adjustment shall be differentiated from spinal manipulation in that the adjustment can only be applied to a vertebral malposition with the express intent to improve or correct the subluxation, whereas any joint, subluxated or not, may be manipulated to mobilize the joint or to put the joint through its range of motion... Chiropractic is a specialized field in the healing arts, and by prior rights, the spinal adjustment is distinct and singular to the chiropractic profession." One author claims that this concept is now repudiated by mainstream chiropractic.[4] The definition of this procedure describes the use of a load (force) to specific body tissues with therapeutic intent. This ‘load’ is traditionally supplied by hand, and can vary in its velocity, amplitude, duration, frequency, and body location and is usually abbreviated HVLA (high velocity low amplitude) thrust.