Unrecognized MS Office files with IGEF headers

[Caleb]

Hi all,
a few years back, I downloaded a torrent full of schematics and other engineering data for various electronic devices. I didn't really look at the files back then, I just put them to archive in case I'll ever need them. It turned out that I did. Among files for one industrial power supply, I found about 30 MS Office files I couldn't open. Even though they have XLS, DOC or PPT extension, they all have "IGEF" string in their headers and TrID couldn't identify them. But these files had similar names and file dates as normal MS Office files in the same directory, so it is unlikely they would just have incorrect extension. My best guess is that some obscure MS Office plugin is requied to open them, but I didn't find even a hint what that could be. Anyway, here are some samples:

http://www.filedropper.com/igefsamples

If you know how to open these files, please let me know.

[Mark0]

Hi!

Thanks for the info and samples.
I don't seems to find any useful info about this files, at the moment, but will try again at another time.

Bye!