I think there may be a problem with how MBED handles non-vanilla file extensions. I have a file in a project with the extension ".properties" that I can't even rename or delete because the filename "contains invalid characters". The only way to remove it would seem to be to delete and re-create the entire project, completely breaking the project's revision control. I also tried to look up the MBED HDK and found that the pdf files were inaccessable. Although I could browse to LPC1768.PDF it proved impossible to get an actual "download" link. When I clicked on the "file" link it just returned the html repository page instead. The Eagle "sch" file might just about be accessable by copying and pasting the XML into notepad, but I don't think it was actually downloadable? I even tried exporting the HDK project to ZIP in the hope that the file would be there, but when I looked inside there was only the firmware "BIN" and some covering notes.