1.1 The Unified Numbering System (UNS) is the accepted alloy designation system in North America for wrought and cast copper and copper alloy products. The designation system is an orderly method of defining and identifying coppers and copper alloys; it is not a specification.

1.2 New designations are assigned as new coppers and copper alloys come into commercial use, and designations are discontinued when an alloy composition ceases to be used commercially. Anyone may request changes in the list.

1.3 New designations are assigned if a copper or copper alloy meets three criteria:
The complete chemical composition is disclosed
The copper or copper alloy is in commercial use or is proposed for commercial use.
The composition does not fall within the limits of any designated composition already in the list.