How do you draw a line. I remember you entered a key then x1,y1, hit a key and entered x2,y2.
Easiest way is with the mouse: Click on the "Line" toolbutton on the Drawing Tools toolbar; click one time in the drawing to set the initial point of the line; move the mouse to the desired location of the end point; click again. That's your basic Line; i.e., it's not drawn between well-defined points. When drawing a line between specific points, those points are usually defined by preexisting objects (a corner of a rectangle and the center of a circle, to cite one of a vast number of possibilities) and one uses an appropriate Snap
mode to set the line's endpoints.
The method you're trying to remember is legitimate, too, but rather laborious IMO: After activating the Line tool, press Shift+Tab to access the X field of the Status Bar and type the X coordinate of the starting point; press Tab to access the Y field and type the Y coordinate of the starting point; press Enter to set that point; press Shift+Tab again to access the X field and type the X coordinate of the finishing point; press Tab to access the Y field and type the Y coordinate of the finishing point; press Enter to finish the line.