A triangular box consists of four dancers. It has three on a diagonal line plus one at a corner of the 3 x 3 matrix of which the line is the diagonal. For example, interlocked blocks (C-1) have two Triangular boxes separated by a line thru the phantom diagonal. Dancers stay in their triangle and work as in a distorted box. See diagram below. Note that triangular boxes are also imbedded in other formations including: 12 matrix, diagonal lines or columns, and parallelogram blocks.