The most obvious description of this in general hypercompact hyperbolic tesselation can be seen from the second row of its incidence matrix: having alternatingly P tets and P octs around each edge.

Incidence matrix according to Dynkin symbol

x3o3oPo4*b   (N,M → ∞)

. . . .    | 2N |  12M | 12pM |  4pM 3pM
-----------+----+------+------+---------
x . . .    |  2 | 12NM |   2p |    p   p
-----------+----+------+------+---------
x3o . .    |  3 |    3 | 8pNM |    1   1
-----------+----+------+------+---------
x3o3o .    ♦  4 |    6 |    4 | 2pNM   *
x3o . o4*b ♦  6 |   12 |    8 |    * pNM