Correction/Addendum for 8 & +9 (both of them) in the above post:
Can be on the nuvi drive or on the SD card (but not both).
Example: You want to add 3D Buildings maps and/or supplemental maps to your nuvi 7x5 device but don't have enough free memory without removing any of the existing map img files. If your not using either or both of the 3D Buildings map names on the nuvi 7x5 drive, you can instead use those map names on the SD card. You can then have 3 img map files always available on an SD card (gmapsupp.img, gmap3d.img & gmap3d1.img).
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