I have no idea if this will help, but a google search for "IEEE_SEND"
brings up three references including an MT-488 PDF Technical Reference.
Chuck Guzis wrote:
  It doesn't correspond to anything that I can
identify, including a
 PDP11.  I'm hoping that some HP aficionado will save me the time of
 plowing through a bunch of HP reference manuals trying to identify
 this thing.
 Again, it might not be HP at all, but the GPIB references may be a
 clue.