DESCRIPTION:
Two steps of seven equal give you a third which is just 4 cents (a fiftieth of a tone) from the 11/9 neutral third (here 11/9 is the ratio of frequencies of the two notes in the dyad).

So - just as a normal diminished seventh is got by stacking equal tempered minor thirds, you get a kind of neutral equivalent of it by stacking these neutral thirds. It has some similarities with the diminished seventh - completely symmetrical so no favoured "root" note. Though it has seven notes instead of four.
Near seven equal tunings are used in Thailand. Also found in parts of Africa.

More about seven equal here:
http://xenharmonic.wikispaces.com/7edo