EVASIVE ACTION DSCNT. ACR IN HOLDING RECEIVES AN RA WHEN A HIGHER ACFT DSNDS TO THE ALT 1000 FT ABOVE THEM AT A HIGH RATE OF DSCNT.

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HOLDING AT EAU VOR ON 123 DEG RADIAL AT FL260. WHILE LEVEL AT FL260 AND TURNING INBOUND TO INTERCEPT THE HOLDING RADIAL; WE RECEIVED A 'DSND NOW' TCASII RA. INTRUDING ACFT WAS SPOTTED DURING EVASIVE MANEUVERING. DSCNT WAS INITIATED TO 200 FT BELOW ASSIGNED FL260. TCASII THEN ISSUED A 'MONITOR DSCNT' WARNING. A RETURN TO ASSIGNED ALT WAS ACCOMPLISHED AND ATC ADVISED OF BOTH TCASII RA AND DSCNT BELOW ASSIGNED FLT LEVEL. WITHOUT QUESTION THIS RA OCCURRENCE WAS A RESULT OF THE ACFT 1000 FT ABOVE US; ALSO IN HOLDING. HE WAS ASSIGNED A DSCNT TO FL270. WE HAD SPOTTED HIM AND NOTED HIS HIGH DSCNT RATE. ACCORDINGLY; THE TCASII RA WAS ISSUED AND WE COMPLIED. DURING THE MANEUVER; WE VISUALLY SPOTTED THE 'INTRUDER' ACFT AND AS NOTED BY TCASII HIS ALT NEVER PENETRATED OUR 1000 FT SEPARATION. HOWEVER; HIS APPARENT HIGH RATES OF DSCNT COUPLED WITH OUR CLOSE PROX TRIGGERED THE TCASII RA -- ANOTHER EXAMPLE OF A 'BUMP' ON TCASII. I CAN'T STRESS THE IMPORTANCE OF LIMITING RATES OF DSCNT TO NO MORE THAN 1000 FPM WHILE IN HOLDING IN CLOSE PROX TO OTHER ACFT.