MDW LCL CTLR ISSUES 'EXIT RWY' AFTER B733 FLC RECEIVES POS AND HOLD CLRNC DUE TO TFC ON SHORT FINAL.

Narrative

NORMAL TAXI OUT TO RWY 31C AT MDW. COMPANY ACFT DEPARTED AHEAD OF US. TWR CALLED US; TOLD TO 'TAXI INTO POS AND HOLD;' BUT USED 'ABCX' INSTEAD OF 'ABCY' FLT NUMBER. I READ BACK ENTIRE CLRNC WITH 'ABCY' EMPHASIZED; WHICH WAS RESPONDED BY HIM WITH AN INFORMAL 'OK' OR 'THAT'S RIGHT.' WE DID BELOW THE LINE AND AS WE TAXIED INTO POS; LOOKED UP TO SEE COMPANY ON SHORT FINAL AND THE CTLR SAYING TO US 'EXIT THE RWY' AND TOLD COMPANY TO GO AROUND. THE CAPT SMOOTHLY KEPT THE TURNOUT ONTO THE RWY AS A TURN OFF THE RWY WITH NO SUDDEN PWR CHANGES OR TILLER MOVEMENT. SHORTLY THEREAFTER; WE RECEIVED TKOF CLRNC. NORMAL TKOF PERFORMED. AS WE CLBED OUT; TWR SWITCHED US TO DEP AND SAID SOMETHING LIKE 'NO PROB' OR 'DON'T WORRY ABOUT WHAT HAPPENED EARLIER' BEFORE HANDING US OVER TO DEP. I COULD HAVE CHKED FINAL TO BE CLR OF TFC BEFORE READING THE CHKLIST IN HAND; BELOW THE LINE PORTION. LESSON LEARNED: LOOK; SEE AND AVOID -- AS TAUGHT 15+ YRS AGO. SUPPLEMENTAL INFO FROM ACN 511687: MY FO VERY CLRLY REPEATED THE CLRNC TO POS AND HOLD SLOWLY SAYING OUR CALL SIGN. AFTER XING THE HOLD SHORT LINE; BUT NOT ON THE RWY; WE WERE TOLD TO CLR THE RWY; WHICH WE DID BY EXECUTING A QUICK 180 DEG TURN. WE WERE RECLRED ONTO THE RWY AND PROCEEDED WITHOUT INCIDENT.