Glossary of "Cladistics (2nd ed.)" by Kitching et al. (1998)
- A square matrix representing the costs of transformation between all states of a character. The values in the upper triangle of the matrix represent the costs in one direction (usually 'forward'), while the values in the lower triangle represent the costs of transformation in the opposite direction.
- Kitching, I. J., Forey, P. L. Humphries, C. J. & Williams, D. M. 1998. Cladistics, 2nd ed.: the Theory and Practice of Parsimony Analysis. -xii + 228 pp. Oxford University Press, New York.