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.
CALL 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.