New text in 4.3.3:

   The main decision is whether the message must be sent in C-mode or
   D-mode.  Reasons for using C-mode are:

[snip]

   o  message size: a message whose size (including the GIST header,
      GIST objects and any NSLP payload, and an allowance for the IP and
      transport layer encapsulation required by D-mode) exceeds a
      fragmentation-related threshold MUST be sent over C-mode.  The
      allowance for IP and transport layer encapsulation is 64 bytes.
      If the Path MTU to the next peer is known, the message size MUST
      NOT exceed that Path MTU; if the Path MTU is not known, the
      message size MUST NOT exceed 576 bytes.


Other minor changes also made as described below.