This document defines the computer programming language PL/I. It is intended to serve as an authoritative reference rather than as a tutorial introduction.
The definition is accomplished by specifying a conceptual PL/I machine which translates and interprets intended PL/I programs. Section 1.1 provides a brief introduction to the statements and data types included in the language, to the structure and use of the document, and to the method of definition. The relationship between an actual implementation and the conceptual machine of this document is described in Section 1.2, and the detailed specification of the notation to be used follows in Section 1.3. The main body of the definition is then begun at Section 1.4, and is completed by Chapters 2 through 9.