BTW I'm working on an Imac (OS 10.6.

I drag the files (I've tried using all three and just BDMV and CERTIFICATE) into the Data section of Toast. Then I select DVD-ROM UDF AND 'BD' from the drop down menu at the bottom of the panel and the disc evidently burns successfully. However, when I put the burnt disc into my Oppo BDP-93 (with latest firmware) I get the message "Warning - This disc will only play in Region B". The Oppo is set to Region B and the original Blu Ray ( which I'm backing up) plays fine. Would really appreciate some advice on this!