Diff bet CallCompletionRate(CCR),CallSuccessRate(CSR)&CallSetupSuccessRate(CSSR)

Can any body tell me the difference between Call Completion Rate (CCR),Call Success Rate (CSR) &

Call Setup Success Rate (CSSR)? I am getting the formula as CCR=call completed/call attempts,

CSR=call successful/call attempt, ASR=call answered / called siezers and CSSR = call set up

successful/call attempt.'

My doubt is what is the diff betn call set up, call success and call completed?