Feet and inches when drawing a line

I've just started using DraftSight today.  Excellent program!

I'm drawing straight lines with ortho on and I want to be able to enter line length in feet and inches (eg. 'L' 8'6 ) in the command line but it only lets me enter in inches.  It works fine with the offset command (eg. I can just type 'O' 8'6 ).

Is there a way to do  this?  Thanks!