With point data a range of core global statistics can be computed. Commonly produced measures of central tendency and spread include: identification of the location of the centre of the point set (typically arithmetic mean, but optionally harmonic and geometric mean centres); identification of the median centre (with or without weights and constraints); and standard distance, weighted standard distance and standard deviational ellipses. Each of these measures has been described earlier in Sections 4.2.5 and 4.5.3. A further measure, provided within some packages, is a table of all pairs of inter-point distances. This matrix is typically symmetric and completely specifies the arrangement of points — i.e. given this distance matrix the point set can be re-constructed, subject only to simple Euclidean transformations (translation, rotation and reflection).