I'm not so sure that gmapprom2.img would be acceptable for a nüvi as mentioned in the previous post. Try gmapprom1.img or gmapsupp.img instead.
SUM files are just check-sum data calculated when the unit uses the diagnostics mode.
The normal map IMG files to use:
- gmapoem.img - Mostly for OEM data with customized POIs for the OEM reseller
- gmapbmap.img - Basemap
- gmapprom.img - Preinstalled map
- gmapprom1.img - Second preinstalled map
- gmapsupp.img - Supplementary map
- gmapsup2.img - Second supplementary map
- gmaptz.img - Time zones
- gmap3d.img - 3D buildings primary map (only compatible units)
- gmap3d1.img - 3D buildings secondary map (only compatible units)