*procedure
**
SENDPKT
      A packet is transmitted, and its return awaited.
      res := sendpkt ( link, id, type, r1, r2, a1,..., a6 )
      The packet which makes up the argument is  sent  using
qpkt, and pktwait called to await its return.
      If the call of qpkt fails  then  sendpkt  aborts  with
code  181; continuing the abort causes a return from sendpkt
with an undefined result.
      Unless the call of pktwait yields the same packet that
was transmitted, sendpkt aborts with  code  182;  continuing
this abort causes it to await the next packet.
      If the packet is transmitted and  received  correctly,
then  the  result  is the value of the pkt.res1 field of the
packet, and the result2 global is set to the pkt.res2 value.


