ANSI INCITS 37: Information Technology - Programming Language APT: Processor Input Language and System-Neutral CLFILE

This standard is a rigorous definition of the APT language and is intended to be used as a reference, rather than tutorial, document. It has been developed and published in this document as a computer based metalanguage in a modified Backus-Naur form. This form is very exacting syntactically and, therefore, can sometimes be difficult to use to construct specific APT statements. To assist in the use of this standard without destroying its rigor, tutorial information has been created. Previously published as a separate Technical Report, this non-normative information consists of explanations of selected capabilities of the language using, prose, examples, and diagrams and, with this revision of the standard, appears in Appendix B of this document.

It establishes the syntax of the APT input (or source) language and the rules governing the interpretation of that syntax. The standard does not prescribe the mechanism or procedure by which the input language is processed. For example, it does not restrict the implementor to the multiple "section" division traditional in the APT community.

With this revision postprocessor language is no longer within the purview of this Standard. Those interested are referred to IS0 4343 for the recommended standard for postprocessor language. This standard also defines the format for the cutter location file (CLFILE), including the tool end positions, all related functions required for the desired operation of the target equipment, and any language deferred for later processing. It provides for a system-neutral format using the ASCII character set to express the output data in a format that is consistent with the APT input language. An ASCII CLFILE format using the traditional class-subclass structure is defined in IS0 3592 and is recommended for use for that purpose.

One of the difficulties stemming from the attempt to provide a complete and rigorous definition of the APT language is the degree to which the standard goes to prevent the language user from creating senseless or unresolvable situations. Although limits and restrictions have been defined into the standard for many foreseeable situations, no attempt has been made to protect the user from foolish language construction. That is, the user is expected to have some knowledge of geometry, machine tools, and other similar skills that would protect the program from illogical geometric constructions.