ARTCC RADAR CTLR HANDED OFF TFC TO APCH CTL. THE TFC AT THE TIME WAS NOT DOWN IN THE APCH CTL AIRSPACE AND ENTERED THE ADJACENT CTR'S AIRSPACE.

Narrative

I WAS WORKING 8-10 OTHER ACFT AT THE TIME. MY MAIN CONCERN WAS TO GET ACFT X BELOW ACFT Y. ACFT Y WAS A DEP OFF LAN TO CVG VIA LFD; FWA VORTAC. ONCE ACFT X WAS UNDER ACFT Y; MY CONCERN WAS TO KEEP ACFT Y BELOW ACFT Z; A DTW INBOUND OVER LFD VORTAC. THE 3 DATA BLOCKS OVERLAPPED AND THE ALT READOUT DROPPED OFF THE ACFT Y DATA BLOCK. I DROPPED THE DATA BLOCK ON ACFT X; AS I HAD SWITCHED HIM TO AZO APCH 5 MI E OF LFD. I FELT A NORMAL RATE OF DSCNT; PLUS AZO APCH WOULD DSND HIM BELOW ZAU AIRSPACE. FOR SOME REASON; ACFT X CHANGED FROM A NORMAL RATE OF DSCNT TO 500-600 FPM. I ALSO LATER FOUND OUT THEY WERE TRAINING ON THE RADAR POS AT AZO APCH; WHICH MAY HAVE DELAYED NORMAL HANDLING A LITTLE. I FAILED TO POINT OUT ACFT X TO THE ZAU KEL SECTOR. WHY DO WE HAVE AN LOA WITH AZO APCH TELLING ZOB TO DSND ARR ACFT TO 11000 FT; AN ALT THEY DON'T OWN; WITH NO ASSURANCE THEY WILL DSND THE ACFT BELOW ZAU AIRSPACE. THE ZAU/ZOB LOA SAYS NOTHING ABOUT HOW AZO APCH ARRS WILL BE HANDLED. OUR ZAU/ZOB LOA DEALS WITH FWA APCH ARRS AS DSND TO 11000 FT AND HAND OFF TO ZAU. THE ARPTS ARE ALMOST SAME DISTANCE FROM CTR BOUNDARIES.