ZOB CTLR EXPERIENCED OPERROR AT FL310 DURING CONFUSION REGARDING DISPLAYED AND ASSIGNED ALT.

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AT APPROX XA07Z; WE WERE FLYING FROM ROC TO MEM. ON CLBOUT; ROC DEP HANDED US OFF TO ZOB WHO CLRED US TO FL270. WE WERE THEN CLRED TO FL330; WHICH I READ BACK AND WAS CONFIRMED BY THE CAPT. PASSING APPROX FL310; WE RECEIVED A TCAS ADVISORY ('TFC; TFC') WHICH BOTH THE CAPT AND I SAW ON THE TCAS AT OUR 12-1 O'CLOCK POS. PASSING APPROX FL317; WE RECEIVED AN RA 'CLB; XING CLB;' AT WHICH POINT THE CAPT ACCOMPLISHED THE APPROPRIATE MANEUVER FOR SEPARATION. CTLR; AT ABOUT THE SAME TIME; TOLD US TO LEVEL OFF AT FL300; BUT THEN TOLD US TO EXPEDITE THROUGH FL320 AFTER I TOLD HIM WE'D BEEN CLRED TO FL330. TCAS THEN GAVE US 'ADJUST VERT SPD' THEN 'CLR OF CONFLICT' CALLS. DURING THIS TIME; I VISUALLY ACQUIRED WHAT APPEARED TO BE A PAX DC9 ALSO EVADING US. WE LEVELED OFF AT FL330; EVENTUALLY BEING CLRED TO FL340. WE SPOKE WITH ZOB ABOUT THE INCIDENT AND THEY STATED THAT THEY HAD SOME CONFUSION ABOUT THE CLRED TO ALT AND THAT NO RPTS WERE REQUIRED ON OUR PART. AS A CREW; WE DID EVERYTHING WE COULD DO CORRECTLY. WX WAS CLR; DAYTIME VFR; WITH ALMOST UNRESTR VISIBILITY. CREW REST WASN'T AN ISSUE AND WE BOTH HEARD FL330; WHICH I READ BACK TO THE CTLR. PROBABLY; THE ONLY ISSUE MIGHT BE DOUBLECHKING WITH ATC AN ALT WHICH MAY NOT BE CORRECT FOR OUR DIRECTION. HOWEVER; WITH THE NEW RVSM ALTS; EVERYONE WILL NEED TO GET USED TO 'ODD' ALTS. TCAS WORKED GREAT. SUPPLEMENTAL INFO FROM ACN 655714: ACFT #1 WAS CLBING TO FL270. ACFT #1 FLASHED AT HIGH ALT. THEY ACCEPTED HDOF; AND ENTERED FL300 AS INTERIM ALT. I ISSUED FL330. AS ACFT #1 LEFT FL300; I QUESTIONED HIM ON ALT. HE REPLIED 'CLBING FL330.' I TOLD HIM TO EXPEDITE THROUGH FL320.