Schematics for limesdr

What is the application is used for the schematics for limesdr, the suffix is .schdoc, and I cannot identify the app to use. I have open office, Eagle, pcsviewer, and kicad, and none can open the schematics. I tried dropping the doc off but still is not recognized.

Altium Designer.

" it’s also only available as an Altium design at this point and not KiCAD yet" -> Is there a LimeSDR 3D Model?

But there are pdf’s of the schematics
socket (micro USB Type-B)
plug (USB Type-A)
EDIT: Mixed up plug and socket, it is A and B, I had B and A.

Thank you, Andrewback, extremely fast reply.

Thank you for the links, mrs. Appreciate the speed of both replies!