What I mean, is over- and under-tones that are not the primary tone of a particular sting/fret combination. When I play each string in turn, I get EeAaDdGgbbee, but when I play only the octave g, I can finger-mute that string, and both my ear and a tuner tell me the g is still being sounded. Working from memory (too lazy to go downstairs and find out for sure,) that tone is coming from the d string, plus one other- even though they are tuned to different pitches. A previous 12-string guitar I had (a Ventura,) did not do that nearly as much.
I really thought "produced tone" was the proper term for these over- and under-tones, but a google search came up dry, so I am not sure if I am remembering my theory correctly. I suppose "harmonics" is either a "better" term, or at least more recognized. But I am sure I am remembering the experience, as described, correctly, even if I am blanking on some of the details.
Of all the 12's I have heard, this one seems to have the most "delicate" tone, too.