There were several UOR bags issued around that time. The mist well known was the PRI(Karrimor) 45 litre. But there was also the ECM Bergen and another one I forget the name of. (Bowman I think?)
One of them was popular because it came with PLCE compatible side pouches which had floating lids and drawstrings. Far superior to the zipped ones.
After Afghan wound down, the army went back to PLCE for a bit for training, issuing new MTP PLCE, including all the old Bergen designs and side pouches. A step backwards really from the UOR stuff.