The user interface shows the move syntax for moving a stack (e.g. “e6-e4”) but not for placing from your stock (simply “e6”, for example).
Though the rules PDF does not show it, the rules as expressed by Sid Sackson include the following: “A move is made in one straight line and can be up, down, to the right, or to the left, but never diagonal.” (A Gamut of Games, p. 127)
When this was pointed out by Lama, Aaron changed the code to prevent diagonal movement. (added by fnord, 2009-06-11, once he found out why he couldn't make the diagonal move he wanted to make)
I am extremely annoyed by PDF files for the rules, as it takes a while and chews up memory on my old laptop to load them, and I am even more annoyed when the rules PDF is a print to PDF of a Wikipedia article which would be less difficult for my computer to handle. Then there are Cell phones and other devices that can't handle PDF at all, like my PSP, so I really dislike having to use it when it is really unnecessary. For anyone else as thoroughly annoyed, or unable to use PDF files, here is the link to the Wikipedia article about Focus. http://en.wikipedia.org/wiki/Focus_(board_game)(added by Krepta3000, 2010-08-08)