1) Demands 2) Do`s 3) Musts 4) Needs 5) Supplies 6) Wants 1) Needs, criteria 
1. The product of a System Analyst's analysis of user's needs. 2. Arbitrary constraints for a computer system, including financial limits, preferential and experiential judgements, contracting loopholes, compatability with legacy systems, and security concerns. 3. A list of a computer system product's capabilities defined after product release. 
Characteristics that identify the accomplishment levels needed to achieve specific objectives for a given set of conditions
A term used in engineering projects to set forth criteria that a project must satisfy. Also applies to the game biz, but the game biz is an entertainment industry, not precisely an engineering discipline. Accordingly, requirements can be more difficult to determine for a game project.