regard BCS item and FI GL

Hi,BCS is new for me,can somebody advise me whats relationship between FS item and GL account?if i manually create FS item in BCS workbench,then i use BW to collect data from SAP,but how can i link those collected data to FS item?

another question,if i execute all consolidation function in BCS,it means there is FS balance in BCS,then i have to present report in BW,how can i use BCS FS balance to create report in BW?I am wondering it there is infocube to store FS item balance?

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