OSDev.org

Or where can I get a definition?

pepito

It simply means very first byte of the file is executable code, and you won't find the specialized sections that other formats have, such as import/export directories, resources, etc.  

It's a binary without any format to it.  In other words, you must setup the environment (data, code segments, etc) yourself... it's basically a glorified boot sector, when you think about it

Cheers,
Jeff

Thank you very much!

pepito