Hello Edison,
Good Day !
I observed that table RESB is giving this information. you can verify through SE11 or SE16 Tcodes. Have an Order number where there are both kinds of Components Reserved and consumed and components Reserved but not consumed. RESB table is having both fields Requirement Quantity (field BDMNG) , and Quantity withdrawn (field ENMNG). So the ifference of these values will be giving the quantity pending. You check this with an Order number and compare these figures with figures in the Order (IW32/33) . If this is the information you are looking for then, create a simple query based on RESB table to have a report and Tcode.
Best of Luck
KJogeswaraRao