CPOE is a software that consists of components like hospital demographic and registration systems, billing systems, clinical information systems, and departmental information systems. CPOE enables the movement of patient information between departments. Data entered in the CPOE can be viewed in legacy software across departments as work progresses from one department to another. The implementation of CPOE reduces the incidence of serious medical error by more than half. This helps to control the number of preventable injuries. However, there is some resistance to CPOE implementation because of the added data entry work it requires from the physicians. At present less than 20% of the hospitals in the US use a CPOE system for ordering medications, diagnostic tests, and ancillary services.