I assume this is a MAP_SET error, no? If yes, I wonder if you are providing illegal values to the LIMIT keyword of that procedure. Through IDL 6.0 there was some issue with some "edge cases" (limits set near, but not over, the allowable value) that occurred due to a mishandling of rounding of values. This was fixed before version 6.1 IDL. If you are still triggering this error, then you probably have to manipulate the values you are providing to MAP_SET's LIMIT keyword. That keyword should have an 4-element (or sometimes 8-element] array with southwestern (or western) coordinates in the first half of the array and northeastern (or eastern) coordinates in the second half of the array. Here is a 4-element array that defines the whole world limit: IDL> MAP_SET, /CONTINENTS, LIMIT=[-180,-90,180,90] James Jones