These are AUI/Loopback connectors.

When you boot a MicroVAX without a network attached it will generally print 
?NI ... at the console and then fail to autoboot. I've got a couple and 
they are useful for machines that are not connected to the network and you 
want to always reboot when they are power cycled.

--Chuck

At 12:43 PM 1/1/02 -0500, you wrote:
>I have 5 DEC...umm, terminators I guess, of some
>sort... 15-pin 'D'-shell type connector, male, with
>only 6 pins in it, and a green LED on the outside,
>DEC P/N 12-22196-01.
>
>Anyone know what they are?
>Anyone have a use for them?
>
>Pete