The Free On-line Dictionary of Computing (30 December 2018):

Core Protocol Stack

   

   1. A portion of the Web Services architecture for
   defining and describing various Web Services.

   2. The architectural protocol layers of a Bluetooth
   wireless communication system, comprising the Host
   Control Interface (HCI), Logical Link Control and Adaptation
   Protocol (L2CAP), RS232 Serial Cable Emulation Profile
   (RFCOMM), Service Discovery Protocol (SDP), and Object
   Exchange (OBEX).

   (2002-06-28)