_SUB FINDCDROM 
    SET-def CDROM=
    FDRV &&All=*:
    SET-def i=0
    FORX * %All%,&&a,
    {   FORM -raw &&T=%&a%
        FIND $DRIVE_CDROM=%&T%,  SET CDROM=%&CDROM% %&a%
    }
    ENVI-ret %1=%&CDROM%
_END

FINDCDROM  &&CDROM
MESS  CDROM [%&CDROM%]