Tiêu chuẩn quốc tế

• Số hiệu / Standard Number: ANSI INCITS 37:1999
• Năm ban hành / Publication date: 1999
• Tình trạng / Status: A - Còn hiệu lực
• Tên tiếng Anh / Title in English: Information Technology - Programming Language APT: Processor Input Language and System-Neutral CLFILE
• Số trang / Page: 474

Phạm vi áp dụng / Scope of standard

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.