DCL:GRPH1:SLPACK: Layout Routines:Explanation of Main Subroutines
The margins are taken so that all of the frames on the current level have the maximum size with the specified aspect ratio.
NumRu::DCL.slrat(rx,ry)
rx, ry (R) Gives the aspect ratio of a frame. For example, if RX=1.0 and ry=1.0, the margins are taken so that the largest possible square frame is set.