From the Wikipedia article about DVD+RW,
DVD+RW supports random write access, which means that data can be added and removed without erasing the whole disc and starting over (up to about 1000 times).While that 'add and remove without erasing the whole disc' thing sounds great, what if you want to erase the disc securely?
Try erasing it with say, K3B, and it'll bail out saying erasing will be done in the background; meaning that if you have 4.4GB of stuff on the disc and you overwrite it with a smaller amount, the old data is still there - Old data which you want to get rid of for some reason (security is a good excuse).
The simplest way of totally erasing a DVD+RW is by writing a 4.4GB ISO which has nothing but 0's in it.
So, from a terminal create the above mentioned disc image using dd.
dd if=/dev/zero of=/tmp/BlankISO.iso bs=1000000 count=4700Now you just have to burn this ISO file onto your DVD+RW and you have a completely empty disc.
P.S : Blanking a DVD+RW actually defeats the purpose of using a DVD+RW but sometimes you just can't help it.