MD88 HOLDING AT CAPTI FL240; CLRED TO DSND TO FL220. CTLR ISSUED VECTOR TURN TO 240 DEGS. BEFORE THE TURN WAS COMPLETED GOT TCASII RA TO DSND. CAPT EXPEDITED DSCNT AND TURN TO FL240. CTLR CALLED TFC THROUGH FL220. TFC SIGHTED VISUALLY AS ACFT LEVELED AT FL210.

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WE HAD BEEN HOLDING AT FL240 OVER CAPTI INTXN FOR NEARLY AN HR. DFW APCH WAS NOT ACCEPTING ANY ARRS DUE TO TSTMS OVER THE ARPT. WE WERE GRADUALLY BEING STEPPED DOWN IN THE HOLDING PATTERN. THE CAPT GAVE ME CTL OF THE AIRPLANE AND STEPPED OUT OF THE COCKPIT TO VISIT THE HEAD. WHILE HE WAS OUT OF THE COCKPIT; ATC TOLD ME TO DSND FROM FL240 TO FL220. I ACKNOWLEDGED THE NEW ALT ASSIGNMENT; INFORMED ATC THAT WE WERE OUT OF FL240 FOR FL220 AND BEGAN A VERT SPD DSCNT. SHORTLY AFTER LEVELING OFF AT FL220 THE CAPT RETURNED AND TOOK CTL OF THE ACFT. MOMENTS LATER; AS WE BEGAN THE SOUTHERLY TURN IN THE PATTERN OVER CAPTI THE CTLR TOLD US TO 'TURN R IMMEDIATELY' TO A HDG OF 240 DEGS. BEFORE THE CAPT COULD INITIATE THE TURN WE RECEIVED A TCASII RA WHICH WAS COMMANDING 'DSND; DSND.' THE CAPT SIMULTANEOUSLY DISENGAGED THE AUTOPLT; BEGAN A DSCNT FOLLOWING THE TCASII PROFILE AND TURNED TOWARDS 240 DEGS. I CALLED ATC; INFORMED THEM WE WERE TURNING TO 240 DEGS AND DSNDING DUE TO A TCASII RA. HE THEN CALLED OUT TFC OPPOSITE DIRECTION THROUGH OUR HOLDING PATTERN AT FL220. WE PICKED UP THE TFC ON TCASII FIRST AT 2 O'CLOCK. AS IT PASSED THROUGH 12 O'CLOCK WE PICKED UP THE TFC VISUALLY. WE LEVELED AT FL210 AS THE TFC PASSED BY US LESS THAN A MI ON OUR L. ATC TOLD THE TFC ( I BELIEVE IT WAS A CITATION) TO TURN TO A HDG (WHICH I CANNOT RECALL) AND TO CLB IMMEDIATELY. I ADVISED ATC WE WERE STEADY ON THE 240 DEG HDG AND LEVEL AT FL210. I ASKED HIM WHAT ALT HE WANTED US AT NOW. HE SAID FL210 WAS FINE; CLRED US DIRECT TO CEDAR CREEK (CQY) AND TOLD US TO EXPECT HOLDING INSTRUCTIONS TO HOLD AT CQY. I SPECIFICALLY ASKED THE CTLR IF HE HAD INDEED ASSIGNED US FL220 IN THE PATTERN PRIOR TO THE CONFLICT. HIS REPLY WAS 'YES' AND WENT ON TO SAY SOMETHING TO THE EFFECT THAT WE HAD BEEN DOING EXACTLY WHAT WE WERE SUPPOSED TO DO. I BELIEVE THIS CONFLICT WAS CAUSED BY A CTLR ERROR. THERE WERE MANY ACFT HOLDING ALL OVER THE DFW AREA WAITING FOR THE ARPT TO REOPEN. IT WAS HECTIC AT BEST WITH NUMEROUS ACFT DIVERTING OR ASKING FOR NEW EFC'S. THIS CTLR WAS TRYING VERY HARD AND GENERALLY DOING A FINE JOB UNDER TRYING CIRCUMSTANCES.