There are several problems in the NJI interface between RSCS V1.3 and
V2.1.  Anyone running such a link should check for fixes to BOTH systems.
With V2 IBM started to actually implement some of the things in the
Protocol Manual (GG22-9373-02 or later)!  (For example, RSCS V2 now actually
uses the 'hold at destination' bit, etc.).
   There have been problems with spanned header records not being handled
right.  I vaguely remember seeing some apars for the '1 second message
delay' (they now pass null records back and forth each second when the
line is idle).  We were getting "BCB Threshold Errors" (VM26766 against
V1R3).  In looking at the traces level 2 thought they saw several other
errors having to do with error recovery.