I don't see any min or max hts in the 2000 IBC. Don't have the 06 yet.
I did find this and its what I need.
NFPA 101
7.10.1.9 Mounting location. The bottom of the marking shall be located at a vertical distance of not more than 6 ft 8 in above the top edge of the egress opening intended for designation by that marking. Egress markings shall be located at a horizontal distance of not more than the required width of the egress opening, as measured from the edge of the egress opening intended for designation by that marking to the nearest edge of the marking.
Thanks, Tim