TARDIS 2005–10, the roundels are built into hexagonal recesses in the walls. Ever since the TARDIS was redesigned at the beginning of the 2010 series, there have been a range of different roundel designs around the console room. These include circular holes that are recessed deep into the walls, hexagonal holes that are lit from behind each face, round indents with brass rings around the outside, and a glass centre that is illuminated blue. In "The Day of the Doctor", when the TARDIS' control room briefly appears as the War Doctor's room, the Eleventh Doctor points out to the Tenth Doctor
Hexagonal lattice term "honeycomb lattice" could mean a corresponding hexagonal lattice, or a structure which is not a lattice in the group sense, but e.g. one in the sense of a lattice model. A set of points forming the vertices of a honeycomb (without points at the centers) shows the honeycomb structure. It can be seen as the union of two offset triangular lattices, shown here red and blue. A triangular lattice itself can be divided into 3 offset triangular lattices, shown above in red, green and blue. A triangular lattice is also called an A2 lattice, A, and the union of