The body of the standard describes the modeling language (syntax and semantics) that supports the IDEF0 method for developing graphical representations of a system or subject area. The clauses that follow govern the physical construction of IDEF0 models that represent functions, functional relationships, and the physical and data objects required by those relationships. This part of the document is divided into 10 clauses. Clause 1 provides an overview of this part of the standard. Clause 2 defines key terms. Clause 3 discusses the concept of an IDEF0 model. Clause 4 defines the syntax of the IDEF0 language. Clause 5 defines the semantics of the language. Clause 6 describes the different types of IDEF0 diagrams. Clause 7 presents the different types of IDEF0 model pages. Clause 8 provides details on the various features of an IDEF0 diagram. Clause 9 defines IDEF0 reference expressions. Finally, Clause 10 defines IDEF0 diagram feature references. Documentation of best commercial practices and guides to recommended usage are beyond the scope of this document.