CUPX format is an extension of the cup format. It is actually a combination of two ZIP files combined in a CUPX file. It can be created by
copy /b pics.zip + points.zip test.cupx
or on linux
cat pics.zip points.zip > test.cupx
The first ZIP file (pics.zip) contains all the images in JPG format in the pics/ folder.
The second ZIP file (points.zip) contains POINTS.CUP that cointains the waypoints with filenames of pictures
corresponding to points in the pics column of the CUP file (without folder name).