CTLR INADVERTENTLY ASSIGNED THE WRONG ALT TO THE SMT; BUT THE ERROR WAS NOT CAUGHT UNTIL ACFT HAD PASSED THROUGH 2 OTHER SECTORS AND LESS THAN STANDARD SEPARATION OCCURRED WITH AN LGT.

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SMT X WAS CLBING TO FLT LEVELS AND HAD TO BE STEPPED UP THROUGH OTHER TFC. ONCE CLR OF ALL TFC IN MY SECTOR; I CLBED SMT X TO HIS REQUESTED ALT (I THOUGHT SO AT THE TIME); WHICH WAS FL210. AFTER LISTENING TO TAPES I INADVERTENTLY CLBED HIM TO FL230. CLOSER OBSERVATION OF DATA BLOCK; FLT PROGRESS STRIPS; AND PLT READ BACK WOULD PROBABLY HAVE AVERTED THE INCIDENT. I WAS UNAWARE THAT IT OCCURRED BECAUSE IT HAPPENED A COUPLE OF SECTORS AWAY AND SMT X WAS A SLOW CLBING ACFT. THE SUPVR NOTIFIED ME. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR SPECIFIED TYPE ACFT THAT SEP WAS LOST WITH AS AN LGT. DATA BLOCK SHOWED SMT CLRED TO FL210 AND ACFT HANDED OFF TO NEXT SECTOR AT 17000'. THE ADJACENT SECTOR HANDED THE SMT OFF TO HIGH ALT SECTOR AND IT WASN'T TILL THE SMT BUSTED THE DATA BLOCK ALT AND HAD THE LTSS THAT THE ERROR WAS DETECTED. TFC WAS SIGHTED BY BOTH ACFT. RPTR WAS WORKING A COMBINED POS OPERATION UNDER LIGHT TO MODERATE CONDITIONS; BUT DIDN'T REALIZE THAT HE HAD GIVEN THE SMT THE WRONG ALT UNTIL SUPVR TOLD HIM OF CONFLICT.