The SE-T084M is an external USB burner with everything but BluRay burning.
RPC1 means removing the region code or region-switching lock from the drive. Normally the DVD drive is set to your region (1..5) so that you can only play DVDs from your region. You can change this region 5 times with the last change being permanently.
RPC1 means removing this limit. Also you can sometimes set your drive to region code 0 which will allow you to play DVDs of any region.
You can enable RPC1 by using MCSE.