/DEVICE_SEED[=value]

    Sets the default starting number (within a range from 1 through
    9999) for the unit numbers that will be assigned to new LTA
    devices. Note that when ports are created by assigning a channel
    to LTA0: with the $ASSIGN system service, the channel numbers
    fall in this same range.

    The default device seed value is approximately half of the
    maximum unit number (which you set by using the /UNIT_NUMBER_
    MAXIMUM qualifier). Interactive LAT ports, and those created
    with the CREATE PORT/LOGICAL command, are assigned unit numbers
    beginning with the specified device seed value and continuing
    up to the maximum unit number. When the maximum unit number is
    reached, the port is assigned the next available unit number
    beginning at the bottom of the range (LTA1:).

    Note that each time you specify the /UNIT_NUMBER_MAXIMUM
    qualifier, the device seed value is reset to approximately half
    of the newly specified maximum unit number.