I'm dealing with codes. The department of making you sad is making me stressed :) I tripped over some information that might be useful to others who need words for codes people who have never heard of anything but tract house construction. It's information on people who passed code for what they were doing, and tells you what exactly they did that made them compliant in the eyes of the inspectors.
Building Innovations Database Example is under "heating and cooling" they have a category for "earthen masonry heater" which is, I suspect, where rocket mass heaters would be listed. I glanced at one of them (Sandoval Masonry Heater) and saw that it's actually a contraflow design, but the way they passed code may be useful to people who are trying to guess how to jump through hoops that are hard to identify.