If anypone has an Oregon x50 series, maps can have any name ending in .img. So Europe 2010 ould be EUNT2010.IMG. This way you can have multiple maps and know by nfilename which is which.
This way you can have an8GB card with maps you are not using at the moment in a top level directory calles say 'Unused Maps' and jus move file to /Garmin/ when you want to use the map.