TRACON APCH CTLR ISSUED INCORRECTLY WORDED APCH CLRNC TO A HOLDING LR35 WITH A DC10 HOLDING 1000 FT BELOW. THE LR35 ACCEPTED THE CLRNC; FOLLOWED THE PUBLISHED PROC AND DSNDED OVER THE TOP OF THE DC10. CTLR RECOGNIZED MISTAKE TOO LATE TO CORRECT ERROR.

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SECOND ACFT WAS A LR35 HOLDING AT MWO FOR THE NDB-A AT 4000 FT. THE LR35 DEPARTED 4000 FT PRIOR TO BEING ESTABLISHED ON THE INBOUND LEG FOR THE APCH. THIS CAUSED A LOSS OF SEPARATION WITH THE DC10 AT 3600 FT. I INSTRUCTED THE LR35 TO CLB TO 4000 FT AND PASSED TFC INFO. THE PLT (LR35) ASKED IF HE WAS STILL CLRED FOR THE APCH. AS TFC WAS NOW NO LONGER A FACTOR; I CLRED HIM AGAIN FOR THE APCH. A MISUNDERSTANDING OCCURRED BTWN LR35 PLT AND CTLR. HE WAS IN A HOLDING PATTERN AND THEREFORE A PROC TURN IS NOT INVOLVED. HOWEVER; IN THE APCH CLRNC; I STATED 'RPT PROC TURN INBOUND.' THIS WAS INCORRECT AND SHOULD HAVE NOT BEEN ACCEPTED BY THE LR35 PLT. HOWEVER; SINCE HE WAS IN HOLDING; HE FAILED TO RPT LEAVING THE HOLDING FIX. MAYBE A BETTER UNDERSTANDING OF HOLDING AND PROC TURNS SHOULD BE TAUGHT TO PLTS AND CTLRS WITH PHRASEOLOGY USED BY BOTH. MWO IS APPROX 30 MI SW OF FFO. SUPPLEMENTAL INFO FROM ACN 391692: WE REQUESTED THE NDB RWY 23 APCH AT MWO (MIDDLETOWN; OH) AND REQUESTED TO SHOOT THE FULL APCH ON OUR OWN. WE RECEIVED CLRNC TO PROCEED TO THE ONIDA NDB FOR THE NDB RWY 23 APCH. PRIOR TO REACHING ONIDA; WE WERE CLRED TO HOLD AS PUBLISHED AT THE BEACON AT 4000 FT DUE TO TFC INBOUND TO THE ARPT. AFTER ENTERING THE HOLD OVER ONIDA WE RECEIVED THE FOLLOWING CLRNC 'CLRED FOR THE NDB RWY 23 AT MIDDLETOWN...MAINTAIN 4000 FT UNTIL PROC TURN INBOUND;' AND WAS READ BACK AS SUCH. NORMALLY WE WOULD BE EXPECTED TO FLY THE APCH FROM THE HOLDING MANEUVER. HOWEVER; SINCE THE ABOVE CLRNC SPECIFICALLY STATED 'PROC TURN;' WE TOOK THIS TO MEAN THAT THE FULL PROC TURN WAS EXPECTED. WITH THIS IN MIND WE DEPARTED THE HOLD; INTERCEPTED THE OUTBOUND COURSE AND BEGAN OUR PROC TURN. AS WE COMPLETED THE OUTBOUND LEG AND PROCEEDED TO TURN TO THE INBOUND HEADING; THE CAPT BEGAN A DSCNT TO THE PUBLISHED INITIAL APCH ALT OF 2600 FT AFTER ROUGHLY 90 DEG OF TURN. (WHICH I BELIEVE TO BE INBOUND; SINCE I/WE ARE NO LONGER 'OUTBOUND.') WHILE DSNDING THROUGH APPROX 3700 FT DAYTON APCH CALLED AND TOLD US TO MAINTAIN 4000 FT FOR TFC AT 3000 FT; PREVIOUSLY UNRPTED TO US THAT WAS ON ANOTHER/DIFFERENT FREQ. THE CAPT STOPPED THE DSCNT AT APPROX 3600 FT AND PROMPTLY RETURNED TO 4000 FT. NEITHER THE CAPT NOR I HAD ANY QUESTION AT WHAT CLRNC WAS ISSUED AND WHAT WAS EXPECTED FROM US. THE COMBINATION OF MIL ACFT OPERATING IN THE SAME AIRSPACE ON SEPARATE FREQ MAY ALSO HAVE BEEN A FACTOR AS SITUATIONAL AWARENESS MAY HAVE PREVENTED THIS.