The Logical Link Controller and Adaptation Protocol which allows packet segmenting and reassembly, as well as high level protocol multiplexing. See Specs page.
Logical Link Control and Adaptation Protocol - Adapts upper layer protocols over the baseband. L2CAP is only defined for ACL links even though the Baseband Protocol is defined for ACL and SCO links.
The Bluetooth Logical Link Control And Adaptation Protocol (L2CAP). It controls how multiple users of the link are multiplexed together, handles packet segmentation and reassembly, and conveys quality of service information.