Aircraft Registration

In the FAA aircraft registration listing on the web there is a section
called Airworthiness. In this section my ASW-19B is listed as having an
Engine Manufacturer of AMA/EXPR and an Engine Model of UNKNOWN ENG.
Three questions about this:

1. EXPR must mean experimental, but what does AMA mean? (There is no
hint in the Definitions menu item for this web site.)

2. I don't think the ASW-19 was ever offered with an engine, so why is
there any listing at all in these two spaces? (I have seen other FAA
glider registrations for ASW-19Bs with NONE in both these areas.)

3. Should I bother to get this changed (does it mean anything, say to
an insurance company) or should I just let sleeping dogs lie?

-John