A detailed description of design criteria for a piece of work

Naming explicitly

(patent law) a document drawn up by the applicant for a patent of invention that provides an explicit and detailed description of the nature and use of an invention

A restriction that is insisted upon as a condition for an agreement

A technical standard is an established norm or requirement for a repeatable technical task which is applied to a common and repeated use of rules, conditions, guidelines or characteristics for products or related processes and production methods, and related management systems practices.

Specificatio is a legal concept adopted from Roman law.

In computer science, formal specifications are mathematically based techniques whose purpose are to help with the implementation of systems and software.

In statistics, model specification is part of the process of building a statistical model: specification consists of selecting an appropriate functional form for the model and choosing which variables to include.