Writing .scr? files for a client HELP

Hi all,

For certain clients of ours we're making screensavers and usualy this implies making several .jpg files so they can chose and decide which of the options we make fit the best for their individual screen. This isn't the problem this is more or less the way we've always done it. 

A day or two ago I got a request from one of them: They asked for an .scr file. this request came from their IT dep. I've never heard of this extention so my first question is what is that file type used for? I've read that it's mainly used for animated screen savers. The project is not in any way shape or form animated and consist out of 4 varients of a design. Yes, they have many aspect ratios but that is litteraly it. 

Seccond question, How would I be able to write that extention without some shady 3rd party software? Can't find actual usefull information what so ever on the interwebs. I suppose that if Adobe doesn't support this extention that it'll be inevitable for me to skip some kind of new software. So if you by any chance know a good reliable solution I'd be all ears.

Thank you for your time and effort.

Yours truely

C