Questions on Virtual Disk's UUID

Hi all,

The API reference does not have much description about Virtual Disk UUID and so I would like to ask couple of questions.

I am referring to the UUID we can retrieve from Virtual Disk's BackingInfo (virtualmachine.config.hardware.device[xxxx].backing.uuid)

1. Is this UUID unique within the vCenter Server?

2. If a disk is detached from the one VM and then attached to another VM, is this UUID guaranteed to remain the same? Assuming that the Virtual Disk's vmdk files were not altered.

Thanks.