A slight clarification...

but loads without extension. this means the file will be in binary format.

The file will be in whatever format you save it out as. A filename extension is merely a 'hint' to (some) OS's as to the format of the file - you could put a .txt extension on a binary file and it'd still be a binary file, or put a .exe extension on a textfile and it'd still load as text.

There's no magic involved in filenames other than that provided by the OS when you launch the file and it decides what application to load (which can be a PITA with MSIE for instance, which prefers the filename extension over the MIME type).

Cheers, Ben.