1. The method, act, process, or effect of using a device or system. 2. A well-defined action that, when applied to any permissible combination of known entities, produces a new entity, e.g., the process of addition in arithmetic--in adding 5 and 3 to obtain 8, the numbers 5 and 3 are the operands, the number 8 is the result, and the plus sign is the operator indicating that the operation performed is addition. 3. A program step, usually specified by a part of an instruction word, that is undertaken or executed by a computer. Note: Examples of operations include addition, multiplication, extraction, comparison, shift, transfer. 4. The process of using a Target of Evaluation.