Hi pete and mahesh,
thanks for your ideas...as per my knowledge if suppose customer has a centrifugal pump (say for example) and in that belt got broken then customer will raise a notification and in reference to notification sales order will be created then the vendor will deliver the belt and raise the bill. Now for fitting new belt to the pump service order will be created. now if I am not wrong in service order, in component tab spare part i.e. belt, will be taken with item category L ( as customer already got belt in stock after delivery). So in cost tab ,belt's cost will also come. now if I will do DP90 with reference to service order. 2 times bill for belt will get generated........ Please correct my knowledge if I am wrong as I am new to this process......I am not creating any contract for this.