.img extension not recognized by Nuvi 350?

[Boyd]

A beta tester of my new map reports that after installing a gmapsupp.img file on his Nuvi 350, it was not recognized. After noticing that the City Navigator maps didn't have a .img extension, he renamed the new map gmapsupp (no extension) and says it now works fine.

I think the Nuvi 350 is one of the first Nuvi's... is it possible this is different from the newer models? Or could it be related to Windows' option of hiding file extensions (mapmaking is one of the only things I do on Windows, so you'll have to help me out here  )

[Boyd]

Heh, I think I see what his problem was. Pretty sure he is using the default Windows folder option to hide file extensions. Before copying a file to the nuvi he re-named it gmapsupp.img but he probably wasn't seeing the invisible .img extension which was already there. Result was a file named gmapsupp.img.img, which wasn't recognized.

Make sense?