RCG and the others....They are based in Austria but the clearing firms are in USA They are introducing brokers....
RCG also uses Patsystems J-trader, TT x-trader and RANorder. RCG also uses ONYX but i don't know how it handles multi-day positions.
No, I do not think so. EasyScreen PLC was an independet ISV, then bought by Refco and now a division of MAREX Financial Ltd.