Pretty sure I did single file BOO updates with the following fields in this order.
ECOGroupID Company Plant PartNum Description RevisionNum OprSeq EstUnitCost OpCode OpDesc ProdStandard StdFormat StdBasis EstScrapType LaborEntryMethod AutoReceive FinalOpr QtyPer ECOOpDtl#OpDtlSeq ECOOpDtl#ResourceGrpID ECOOpDtl#ResourceID ECOOpDtl#OpDtlDesc
2nd single DMT file BoM Fields I used were:
ECOGroupID Company Plant PartNum RevisionNum MtlSeq MtlPartNum RelatedOperation FixedQty EstScrapType QtyPer UOMCode ViewAsAsm PlanAsAsm PullAsAsm