This draft standard is a rigorous definition of the APT language and is intended to be used as a reference, rather than a tutorial. It establishes the syntax of the APT input (or source) language and the rules governing the interpretation of that syntax. It also defines the format for the cutter location file (CLFILE). It provides for both the traditional class-subclass format, and for a new format using the ASCII character set to express the output data in formats that are consistent with the APT input language.