what is heater multiword cable

Multiword cable is a multi-width cable, with one dedicated to the transfer of multiword messages, for example a multiword dual DMA. I don't know what the "heater" refers to though, you'll have to wait for someone else to post, I can only offer partial answer. Might be a multiword message cable for a heater? I will watch for a full answer and learn also, but this partial answer may be of some use to you.