Dear, CM! Who are you asking such strange questions? BSC? PCU? RLC\MAC entity?:) All procedures in question you may seek in 44.060 (for RLC\MAC), 44.018 (for Packet Channel Request and Immediate Ass when there is no PCCCH), 43.064 (for GPRS radiointerface), 45-series (for phisical layer). What else? You also must take in account GPRS BCCH info for MS (e.g. CONTROL_ACK_TYPE etc.) – 24.008 and 44.060.
It is very difficult to understand anything from your description. Give us more info about messages sequences (from beginning) and the key parameters of the messages.