libvirt users - Apr 2011 - Adding more disks...

I need a VM with about 6-8 qcow2 disk images, but it
seems to only allow 4 disks on the ide, like the real
hardware. What lines do you need to add on to the xml
definition file to get hde, hdf, hdg, etc?

I did not find documentation but I managed by 
guessing:

<target dev='sde' bus='scsi' />

did the trick. Is this stuff fully documented
anywhere?