This diminishing of ope takes place at the vertices of an inscribed q-tet. The latter can be considered as a digonal antiprism with its degenerate bases being arbitrary non-parallel diagonals of the (former) octs.

Incidence matrix according to Dynkin symbol

((oo qo oq))&#zx || ((qo oo oq))&#zx   → height = 1
(square (in rhombic position) atop partly orthogonal square (in rhombic position))

  o. o. o.           .. .. ..       | 2 * * * | 2 2 2 0 0 0 | 1 4 2 4 0 0 | 2 4 1
  .o .o .o           .. .. ..       | * 2 * * | 2 0 0 2 1 0 | 1 4 2 0 2 0 | 2 4 0
  .. .. ..           o. o. o.       | * * 2 * | 0 2 0 2 0 2 | 0 4 0 4 2 1 | 1 4 2
  .. .. ..           .o .o .o       | * * * 2 | 0 0 2 0 1 2 | 0 0 2 4 2 1 | 0 4 2
------------------------------------+---------+-------------+-------------+------
  oo oo oo  &#x      .. .. ..       | 1 1 0 0 | 4 * * * * * | 1 2 1 0 0 0 | 2 2 0 x
  o. o. o.       ||   o. o. o.       | 1 0 1 0 | * 4 * * * * | 0 2 0 2 0 0 | 1 2 1 q
  o. o. o.       ||   .o .o .o       | 1 0 0 1 | * * 4 * * * | 0 0 1 2 0 0 | 0 2 1 q
  .o .o .o       ||   o. o. o.       | 0 1 1 0 | * * * 4 * * | 0 2 0 0 1 0 | 1 2 0 q
  .o .o .o       ||   .o .o .o       | 0 1 0 1 | * * * * 2 * | 0 0 2 0 2 0 | 0 4 0 x
  .. .. ..           oo oo oo  &#x  | 0 0 1 1 | * * * * * 4 | 0 0 0 2 1 1 | 0 2 2 x
------------------------------------+---------+-------------+-------------+------
((.. qo oq))&#zx     .. .. ..       | 2 2 0 0 | 4 0 0 0 0 0 | 1 * * * * * | 2 0 0  x-{4}
  oo oo oo  &#x  ||   o. o. o.       | 1 1 1 0 | 1 1 0 1 0 0 | * 8 * * * * | 1 1 0  {xqq}
  oo oo oo  &#x  ||   .o .o .o       | 1 1 0 1 | 1 0 1 0 1 0 | * * 4 * * * | 0 2 0  {xxq}
  o. o. o.       ||   oo oo oo  &#x  | 1 0 1 1 | 0 1 1 0 0 1 | * * * 8 * * | 0 1 1  {xqq}
  .o .o .o       ||   oo oo oo  &#x  | 0 1 1 1 | 0 0 0 1 1 1 | * * * * 4 * | 0 2 0  {xxq}
  .. .. ..         ((qo .. oq))&#zx | 0 0 2 2 | 0 0 0 0 0 4 | * * * * * 1 | 0 0 2  x-{4}
------------------------------------+---------+-------------+-------------+------
((.. qo oq))&#zx ||   o. o. o.       | 2 2 1 0 | 4 2 0 2 0 0 | 1 4 0 0 0 0 | 2 * *  ox4oo&#q
  oo oo oo  &#x  ||   oo oo oo  &#x  | 1 1 1 1 | 1 1 1 1 1 1 | 0 1 1 1 1 0 | * 8 *  (x-x-x,q-q-q) simplex
  o. o. o.       || ((qo .. oq))&#zx | 1 0 2 2 | 0 2 2 0 0 4 | 0 0 0 4 0 1 | * * 2  ox4oo&#q

or
  o. o. o.           .. .. ..       & | 4 * | 2 2 2 0 | 1  8 2 | 3 4
  .o .o .o           .. .. ..       & | * 4 | 2 0 2 1 | 1  4 4 | 2 4
--------------------------------------+-----+---------+--------+----
  oo oo oo  &#x      .. .. ..       & | 1 1 | 8 * * * | 1  2 1 | 2 2  x
  o. o. o.       ||   o. o. o.         | 2 0 | * 4 * * | 0  4 0 | 2 2  q
  o. o. o.       ||   .o .o .o       & | 1 1 | * * 8 * | 0  2 1 | 1 2  q
  .o .o .o       ||   .o .o .o         | 0 2 | * * * 2 | 0  0 4 | 0 4  x
--------------------------------------+-----+---------+--------+----
((.. qo oq))&#zx     .. .. ..       & | 2 2 | 4 0 0 0 | 2  * * | 2 0  x-{4}
  oo oo oo  &#x  ||   o. o. o.       & | 2 1 | 1 1 1 0 | * 16 * | 1 1  {xqq}
  oo oo oo  &#x  ||   .o .o .o       & | 1 2 | 1 0 1 1 | *  * 8 | 0 2  {xxq}
--------------------------------------+-----+---------+--------+----
((.. qo oq))&#zx ||   o. o. o.       & | 3 2 | 4 2 2 0 | 1  4 0 | 4 *  ox4oo&#q
  oo oo oo  &#x  ||   oo oo oo  &#x    | 2 2 | 2 1 2 1 | 0  2 2 | * 8  (x-x-x,q-q-q) simplex

oqo ooo&#xt || ooo oqo&#xt   → height = 1

o.. o..       ... ...     | 1 * * * * * | 2 1 2 0 0 0 0 0 0 0 0 | 1 2 4 2 0 0 0 0 0 0 | 2 4 0 0
.o. .o.       ... ...     | * 2 * * * * | 1 0 0 1 1 2 1 0 0 0 0 | 1 1 2 0 2 1 2 2 0 0 | 2 2 2 1
..o ..o       ... ...     | * * 1 * * * | 0 0 0 2 0 0 0 2 1 0 0 | 1 0 0 0 4 2 0 0 2 0 | 2 0 4 0
... ...       o.. o..     | * * * 1 * * | 0 1 0 0 2 0 0 0 0 2 0 | 0 2 0 2 0 0 4 0 0 1 | 0 4 0 2
... ...       .o. .o.     | * * * * 2 * | 0 0 1 0 0 2 0 1 0 1 1 | 0 0 2 1 2 0 2 2 1 1 | 1 2 2 2
... ...       ..o ..o     | * * * * * 1 | 0 0 0 0 0 0 2 0 1 0 2 | 0 0 0 0 0 2 0 4 2 1 | 0 0 4 2
--------------------------+-------------+-----------------------+---------------------+--------
oo. oo.&#x    ... ...     | 1 1 0 0 0 0 | 2 * * * * * * * * * * | 1 1 2 0 0 0 0 0 0 0 | 2 2 0 0  x
o.. o..     || o.. o..     | 1 0 0 1 0 0 | * 1 * * * * * * * * * | 0 2 0 2 0 0 0 0 0 0 | 0 4 0 0  x
o.. o..     || .o. .o.     | 1 0 0 0 1 0 | * * 2 * * * * * * * * | 0 0 2 1 0 0 0 0 0 0 | 1 2 0 0  q
.oo .oo&#x    ... ...     | 0 1 1 0 0 0 | * * * 2 * * * * * * * | 1 0 0 0 2 1 0 0 0 0 | 2 0 2 0  x
.o. .o.     || o.. o..     | 0 1 0 1 0 0 | * * * * 2 * * * * * * | 0 1 0 0 0 0 2 0 0 0 | 0 2 0 1  q
.o. .o.     || .o. .o.     | 0 1 0 0 1 0 | * * * * * 4 * * * * * | 0 0 1 0 1 0 1 1 0 0 | 1 1 1 1  q
.o. .o.     || ..o ..o     | 0 1 0 0 0 1 | * * * * * * 2 * * * * | 0 0 0 0 0 1 0 2 0 0 | 0 0 2 1  q
..o ..o     || .o. .o.     | 0 0 1 0 1 0 | * * * * * * * 2 * * * | 0 0 0 0 2 0 0 0 1 0 | 1 0 2 0  q
..o ..o     || ..o ..o     | 0 0 1 0 0 1 | * * * * * * * * 1 * * | 0 0 0 0 0 2 0 0 2 0 | 0 0 4 0  x
... ...       oo. oo.&#x  | 0 0 0 1 1 0 | * * * * * * * * * 2 * | 0 0 0 1 0 0 2 0 0 1 | 0 2 0 2  x
... ...       .oo .oo&#x  | 0 0 0 0 1 1 | * * * * * * * * * * 2 | 0 0 0 0 0 0 0 2 1 1 | 0 0 2 2  x
--------------------------+-------------+-----------------------+---------------------+--------
oqo ...&#xt   ... ...     | 1 2 1 0 0 0 | 2 0 0 2 0 0 0 0 0 0 0 | 1 * * * * * * * * * | 2 0 0 0  x-{4}
oo. oo.&#x  || o.. o..     | 1 1 0 1 0 0 | 1 1 0 0 1 0 0 0 0 0 0 | * 2 * * * * * * * * | 0 2 0 0  {xxq}
oo. oo.&#x  || .o. .o.     | 1 1 0 0 1 0 | 1 0 1 0 0 1 0 0 0 0 0 | * * 4 * * * * * * * | 1 1 0 0  {xqq}
o.. o..     || oo. oo.&#x  | 1 0 0 1 1 0 | 0 1 1 0 0 0 0 0 0 1 0 | * * * 2 * * * * * * | 0 2 0 0  {xxq}
.oo .oo&#x  || .o. .o.     | 0 1 1 0 1 0 | 0 0 0 1 0 1 0 1 0 0 0 | * * * * 4 * * * * * | 1 0 1 0  {xqq}
.oo .oo&#x  || ..o ..o     | 0 1 1 0 0 1 | 0 0 0 1 0 0 1 0 1 0 0 | * * * * * 2 * * * * | 0 0 2 0  {xxq}
.o. .o.     || oo. oo.&#x  | 0 1 0 1 1 0 | 0 0 0 0 1 1 0 0 0 1 0 | * * * * * * 4 * * * | 0 1 0 1  {xqq}
.o. .o.     || .oo .oo&#x  | 0 1 0 0 1 1 | 0 0 0 0 0 1 1 0 0 0 1 | * * * * * * * 4 * * | 0 0 1 1  {xqq}
..o ..o     || .oo .oo&#x  | 0 0 1 0 1 1 | 0 0 0 0 0 0 0 1 1 0 1 | * * * * * * * * 2 * | 0 0 2 0  {xxq}
... ...       ... oqo&#xt | 0 0 0 1 2 1 | 0 0 0 0 0 0 0 0 0 2 2 | * * * * * * * * * 1 | 0 0 0 2  x-{4}
--------------------------+-------------+-----------------------+---------------------+--------
oqo ...&#xt || .o. .o.     | 1 2 1 0 1 0 | 2 0 1 2 0 2 0 1 0 0 0 | 1 0 2 0 2 0 0 0 0 0 | 2 * * *  ox4oo&#q
oo. oo.&#x  || oo. oo.&#x  | 1 1 0 1 1 0 | 1 1 1 0 1 1 0 0 0 1 0 | 0 1 1 1 0 0 1 0 0 0 | * 4 * *  (x-x-x,q-q-q) simplex
.oo .oo&#x  || .oo .oo&#x  | 0 1 1 0 1 1 | 0 0 0 1 0 1 1 1 1 0 1 | 0 0 0 0 1 1 0 1 1 0 | * * 4 *  (x-x-x,q-q-q) simplex
.o. .o.     || ... oqo&#xt | 0 1 0 1 2 1 | 0 0 0 0 1 2 1 0 0 2 2 | 0 0 0 0 0 0 2 2 0 1 | * * * 2  ox4oo&#q