as per PM:
The data format within the file is "foldername\musicfilename.mp3" on each line, format is the earlier VERY simple m3u format: no drive letter, but you need to have a relative path... so when you place the M3U in the root, it can find the files in the sub-folders.
Here's a sample:
"100 years of the Movies\1 - BBC Concert Orchestra - That's Entertaiment.mp3
100 years of the Movies\4 - BBC Concert Orchestra - The Dam Busters.mp3
100 years of the Movies\5 - BBC Concert Orchestra - The King & I - Shall we dance.mp3
100 years of the Movies\6 - BBC Concert Orchestra - The Bridge over the River Kwai.mp3"
Don't stress about the win7 "XP-Mode" - the SD cardreader simulation still doesn't let you export directly to the SD card (so you still have to do the steps below).
Setup a folder for RNS-E music on a drive (e.g. "C:\RNS-E-Music") and then a subfolder (e.g. "SDcard1"), then copy the music you want into folders in that "SDcard1" folder, create M3U's using VLC* media player or something like that and place the M3U's into the root ("C:\RNS-E-Music" in this example) and then when you're all done, open the M3U in notepad and strip out the extra info: just do a replace (Ctrl-H) on the first part of the path "C:\RNS-E-music\" and leave the "Replace With" field completely blank. Then move those M3U's and subfolders (containing the music) onto the SD card.
*note with VLC, you will also have to delete all the # lines, which is easy enough with Notepad++ or something like that. Ideally find something that has even more simple M3U formatting - windows Media Player produces the same formatted M3U files IF you switch it to M3U mode.... maybe somebody can recommend a SIMPLE M3U file creator?