Custom framers will over still design a presentation with matting below artwork thus creating a "space" between the edge of the artwork and the frame itself. Often this is done to enhance the dimensional aspects of the art or to show off an unusual edge.

It doesn't have a name in particular but you are correct in that it creates a clean look. Depending upon the artwork, different structurally sound methods need to be incorporated to assure that the artwork is still secure and mounted in place.

Some framers may refer to this as "floating the artwork" above the mat or background.

Sincerely,