Each ExpertGPS map is composed of the scanned map/airphoto, etc., as a .jpg file and a .map file containing the info about the map coordinates. The .jpg file must retain the same path recorded in the .map file; if the path is changed the reference in the .map file must be changed (Wordpad will do). In the .map text file "Name" refers to the .map file, whereas "Location" refers to the path to the .jpg map. The .map file can be archived anywhere but for it to appear in ExpertGPS it must be retained in the same archive as when it was imported into ExpertGPS. In other words, ExpertGPS stores the location of the .map file and the .map file stores the location of the .jpg.  For each computer with ExpertGPS the .map files must be re-imported into ExpertGPS.  
 
The actual map .,jpg is in \fieldlog\sapp whereas the ExpertGps map file is in \fieldlog\sapp\expertgpsmap. 
The map file looks like:

User Map Calibration File Version 2.2
sapppav164a.jpg (name of map file)
C:\fieldlog\Sapp\sapppav164a.jpg (location of the image)
1 ,Map Code,
WGS 84,WGS 84,   0.0000,   0.0000,WGS 84
Reserved 1
Reserved 2
Magnetic Variation,,,E
Map Projection,Latitude/Longitude,PolyCal,No,AutoCalOnly,No,BSBUseWPX,No
Point01,xy,  541, 1473,in, deg,  38,  30.002,N,  77,  37.482,W, grid,   ,           ,           ,N
Point02,xy, 1669, 1484,in, deg,  38,  30.000,N,  77,  22.500,W, grid,   ,           ,           ,N
Point03,xy, 1674,   59,in, deg,  38,  45.000,N,  77,  22.500,W, grid,   ,           ,           ,N
etc., etc.