I know that official SDKs and enterprises develop DS games as SRL format, which is (more or less) like a NDS ROM, but the main problem is that they both have file systems, but in a different way.
Common editors like EFE or MKDSCM can access NDS ROMs' fs, but I have no idea even if there are any tools or people which can or managed to access SRL ROM's fs.
Anyone knows something about this?
Also, I must comment that both ROM types are generally supported by emulators (official SRLs work on Desmume and on R4 cartridges, after renaming extension to NDS, and also people say that they work on NO$GBA)
Also, I can test on SRLs (because I have a few SRLs), but for the moment I've just tried to losd them on R4 renaming their extension, and they worked correctly.