Names must begin with an alphanumeric character. Yes results in scrollbars always being visible on that frame. No results in scrollbars never being visible. Auto instructs the browser to decide whether scrollbars are needed, and place them where necessary. It is a flag that indicates that the frame is not resizable by the user.
Users typically resize frames by draggin a frame edge to a new position.
Note that if any frame adjacent to an edge is not resizable, that entire edge will be restricted from moving. This will effect the resizability of other frames.