Hi guyenvmware000,
Our EFI implementation does not include full support for long filenames on FAT filesystems, so by default you'll be unable to create non-"8.3" filenames from within EFI. If you need long filename support, you'll have to obtain or build a FAT filesystem driver with that support, and load it into the EFI environment. (The driver source is here).
Cheers,
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Darius