In article . net,
Steven P. McNicoll wrote:

"EDR" wrote in message
...

As Paul said, there is a Letter of Agreement.
The Columbus OH airspace has three CDAS beneath the
KCMH CCAS. There is a LOA between Columbus and
each of the three satellites that reduces the CDAS from 4000
AGL to 2500 AGL, giving the CCAS Approach control the
airspace 2500 and above. (Note that 2500 AGL is the floor
of the CCAS surrounding Columbus.)


The standard for Class D airspace is 2500' AGL. The standard for the ten
mile ring of Class C airspace is 1200' to 4000' AGL. The OSU and TZR Class
D airspace areas use the standard, the LCK Class D airspace ceiling is 2300'
AGL. The CMH ten mile Class C ring is 1700' to 4000' AGL.

OOPS!!!
That should have been MSL in posting.
I knew that, I was the one that petitioned to make it uniform back in
the early 1990's.