The importance of this test rests on the fact
that the dimensions of the fabricated modules must be within some tolerances
(vertex coordinates: 
, neighbor side angles:
, and opposite side angles: 
) of
theoretical dimensions --- these dimensions are given in the tables and figures of
section 5.4 --- to successfully put together the
calorimeter. Therefore, the dimensions of the delivered crystals are examined
using a 3-dimensional measuring device. The device is computer controlled and
automatically scans the surfaces, picking six points on each of the surfaces of
the crystal whose dimensions are being checked. The selected points are fitted
with planes, and the coordinates of the vertices follow as intersections of
planes. The absolute precision of the device is 
with a
reproducibility of 
.