This command executes the PEDRIVER specific SDA extension image
    which is a collection of PEDRIVER specific commands which mirror
    the display functions of SYS$SYSTEM:SCACP.EXE in SDA.

    By default this image is loaded from SYS$SHARE.  However, it can
    be redirected with the following logical:

 	$ define pe$sda [dir-spec]pe$sda.exe

    Format:

 	SDA> PE command