It may differ from vendor to vendor. In Ericsson we have 3 different lists :
1- Active Mode BA List
2- Idle Mode BA List
3- Neighbor list.
Active Mode BA list is sent in SI5 and it tells the MS which BCCHs should be measured in dedicated mode and reported back.Idle mode BA List is sent in SI2 and tells the MS which BCCHs should be measured in Idle Mode for cell reselection. Neighbor list is in BSC and not sent to MS, it is used for handover decisions. Logically every neighbor BCCH should be part of active mode BA list otherwise there will be no handover. If a BCCH is part of Active BA List and is not defined as a neighbor, it will be reported in measurement reports but will be discarded and no handover command will be sent. If BCCH of a neighbor is not part of active BA list then it wont be measured by MS and hence no handover 🙂