ORD DEP AWAITING TKOF FROM RWY 4L; CROSSED HOLD LINE; TOLD TO HOLD POSITION AND THEN OBSERVED SEVERAL ACFT DEP RWY FROM OPPOSITE SIDE.

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WE HAD A WHEELS-UP DELAY. OUR TIME WAS XA17 WITH AN ORIGINALLY SCHEDULED XB45 DEP. BOARDING WAS DELAYED UNTIL XC10. WE TAXIED OUT AND WERE TOLD THAT OUR TIME HAD CHANGED TO APPROX XA00. OUR TAXI CLRNC FROM THE S PORT WAS TXWY B; TXWY E; RWY 4L. WE TOLD GND NEARING TXWY E THAT WE WERE AWAITING OUR NUMBERS. WHEN WE DID NOT HAVE THEM BY ABOUT XA00; WE WERE TOLD TO CROSS RWY 4L; DO A 180 DEG TURN; AND HOLD SHORT ON THE NW SIDE AT RWY 4L. WE DID. AT APPROX XA09 TWR CLRED US INTO POS AND HOLD ON RWY 4L WHEN TOLD WE HAD OUR NUMBERS. WE BEGAN TO TAXI INTO POS AND WERE 1/2 WAY ACROSS THE HOLD LINE WHEN WE WERE TOLD TO 'HOLD POS.' WE STOPPED WITH THE TAIL ABOUT AT THE HOLD LINE AND TOLD TWR THAT WE WERE ACROSS THE HOLD SHORT LINE FOR THE RWY. HE REPLIED 'THAT'S OK; JUST HOLD YOUR POS.' HE THEN CLRED 3 DIFFERENT ACFT INTO POS AND SUBSEQUENTLY TO TKOF. I DETERMINED WE HAD ABOUT 75 FT CLRNC AND ELECTED TO STAY PUT AS IT SEEMED TO BE THE SAFEST COURSE OF ACTION. WE WERE THEN CLRED TO TAKE OFF NORMALLY. IT SEEMED VERY ODD TO BE TOLD TO STOP AFTER XING THE HOLD LINE; AND THEN CONFIRM THAT WITH TWR; AND WATCH 3 PLANES TAKE OFF.