This parameter value determines the maximum size of an
end-to-end segment. The size is a decimal integer in
the range 1-65535. This size is in bytes. This size
includes protocol overhead down to and including the
End Communication layer, plus a constant value of 6.
(This value of 6 is included to provide compatibility
with the BUFFER SIZE parameter definition.) It does not
include Routing or Data link overhead (except for the
constant value of 6).