What are references within CPC titles and how do they function?

References within CPC titles are statements enclosed in parentheses that point to other classification places of interest. They apply to the classification place where they appear and all hierarchically lower places, unless stated otherwise. There are two main types of references:

• Limiting references: These exclude specific subject matter from the scope of the classification place. As stated in the MPEP, “Limiting references are pertinent for classification purposes. Limiting references limit the scope of a place, thereby avoiding overlap.“
• Precedence references: These are special limiting references that refer to other groups taking “precedence” within the same subclass, used to remove overlap between similar groups.

For example, a limiting reference: “B64C AEROPLANES; HELICOPTERS (air-cushion vehicles B60V)” excludes air-cushion vehicles from B64C, directing them to B60V instead.

To learn more:

• CPC
• References
• Limiting References
• Precedence References
• Patent Classification