cross at or below
cross (fix) at or below (altitude)
An instruction used by ATC (air traffic control) when a maximum crossing altitude at a specific fix is required. It does not prohibit the aircraft from crossing the fix at a lower altitude; however, it must be at or above the minimum IFR (instrument flight rules) altitude.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved