Following their basic and advanced training at the individual-level, soldiers may choose to continue their training and apply for an "additional skill identifier" (ASI). The ASI allows the army to take a wide ranging MOS and focus it into a more specific MOS. For example, a combat medic, whose duties are to provide pre-hospital emergency treatment, may receive ASI training to become a cardiovascular specialist, a dialysis specialist, or even a licensed practical nurse. For commissioned officers, ASI training includes pre-commissioning training either at USMA, or via ROTC, or by completing OCS. After commissioning, officers undergo branch specific training at the Basic Officer Leaders Course, (formerly called Officer Basic Course), which varies in time and location according their future assignments. Further career development is available through the Army Correspondence Course Program.