ISO/IEC 13211-1:1995

Designed to promote the applicability and portability of Prolog text and data among a variety of data processing systems. Specifies: the representation of Prolog text; the syntax and constraints of the Prolog language; the semantic rules for interpreting Prolog text; the representation of input data to be processed by Prolog; the representation of output produced by Prolog and the restrictions and limits imposed on a conforming Prolog processor.