TIDA-010030: Pack+ measurement

On page 16 of TIDA-010030 design guide (TIDUEG78.pdf), there is step "measure pack+' that I am not quite sure how to measure it with i2c reading.

I am assuming it is a register read of bq76940, "CELL VOLTAGE REGISTERS" of the highest cell like C13? But C13 is not equal to PACK+, is it? Or 'measure pack+" actually mean "measure bat+'? If it really means pack+, how can I measure it with register read? Thanks

Eric