Specification (often abbreviated as spec) may refer to an explicit set of requirements to be satisfied by a material, design, product, or service. Should a material, product, or service fail to meet one or more of the applicable specifications, it may be referred to as being out of specification; the abbreviation OOS may also be used. In casual usage, underspec or overspec are used when something is worse or better than specified (compare overengineering), though in general (such as for sizes) there is only a notion of "in spec" or "out of spec", not "better" or "worse". A specification is a type of technical standard.A technical specification may be developed by any of various kinds of organizations, both public and private. Example organization types include a corporation, a consortium (a small group of corporations), a trade association (an industry-wide group of corporations), a national government (including its military, regulatory agencies, and national laboratories and institutes), a professional association (society), a purpose-made standards organization such as ISO, or vendor-neutral developed generic requirements. It is common for one organization to refer to (reference, call out, cite) the standards of another. Voluntary standards may become mandatory if adopted by a government or business contract.A Design or Product Specification describes the features of the solutions for the Requirement Specification. Sometimes the term specification is here used in connection with a data sheet (or spec sheet). This may be confusing. A data sheet describes the technical characteristics of an item or product as designed and/or produced. It can be published by a manufacturer to help people choose products or to help use the products. A data sheet is not a technical specification as described in this article.