BTC
Before Top Center crank position
BTC
Bit Test and Complement
AAL
Asynchronous transfer mode (ATM) Adaptation Layer
AAL1
Asynchronous transfer mode (ATM) Adaptation Layer 1
AAL2
Asynchronous transfer mode (ATM) Adaptation Layer 2
AAL3
Asynchronous transfer mode (ATM) Adaptation Layer 3
AAL4
Asynchronous transfer mode (ATM) Adaptation Layer 4