I have the Sony DRU500A, and it is supposed to support both -R and +R. But...how am I supposed to choose which format to burn? The software packing it comes with has no way of specifying which format I would like to burn with (-R or +R)? Or is the format on the DVD disc itself? Meaning...the DRU500A can burn both -R and +R discs...versus being able to choose the format on the recording software?