TKOF BELOW MINIMUM RVR.

Narrative

WHILE TAXIING OUT FOR TKOF AT MCO RWY VISIBILITY WAS RPTED AS 6; 6; AND 6 SEVERAL TIMES. WHEN #1 FOR TKOF; TWR RPTED RVR LESS THAN 600 FT CAN YOU GO? WE MISUNDERSTOOD TWR; STILL HAVING A 600 FT RVR MINDSET; AND REPLIED YES. WE WERE CLRED FOR TKOF. DURING TKOF ROLL WE HEARD TWR TALKING TO OTHER AIRLINE ACFT AND REALIZED THAT THE TWR HAD PROBABLY RPTED THE RVR AT LESS THAN 600 FT AND WE ACTUALLY WERE NOT LEGAL FOR TKOF. I CONSIDERED IT SAFER TO CONTINUE THE TKOF; RATHER THAN MAKE A HIGH SPD ABORT IN THE FOG. TKOF WAS NORMAL; AND WE CONTINUED ON TO IAH. SUPPLEMENTAL INFO FROM ACN 295174: AFTER OUR TKOF ROLL HAD BEEN INITIATED; TWR CONTACTED THE NEXT ACFT IN LINE FOR TKOF (ANOTHER AIRLINE FLT) AND ADVISED THEM THAT RVR FOR RWY 36R WAS LESS THAN 600 FT; COULD THEY ACCEPT A TKOF. THE OTHER AIRLINE RESPONDED THAT THEY NEEDED 600 FT RVR AND; THEREFORE; COULD NOT TKOF. AFTER TKOF; I QUESTIONED IF TWR HAD ALSO GIVEN US LESS THAN 600 FT RVR; BUT THIS INFO WAS MISINTERPRETED DUE TO COMPLETION OF THE BEFORE TKOF CHKLIST. NO UNUSUAL OR DANGEROUS SIT RESULTED FROM THE DECISION TO CONTINUE THE TKOF.