In a single word, "directions"...
...WPS is an abbreviation for "Welding Procedure Specification". Various standards (code) established by AWS, ANSI, and similar organizations specify procedures to be used by welders in order insure a uniform quality, or repeatablility, of the welds.
It specifies a range within which all variables and details related to the weld must be... the procedure... in hopes the weldment will behave in a predictable manner as anticipated by the [engineer].
Associated with the WPS is the WPQR; the qualification record of specifics the welder used to make a weldment which passed tests according to standards published by the organizations previously mentioned, and the results of that testing.
You might think of it in the context of an important legal record. It's purpose is to insure safety.
Regards,
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