Glossary of "Cladistics (2nd ed.)" by Kitching et al. (1998)
- A multistate character of which the order has not been determined. In an unordered character, transformation between any two states, whether adjacent or non-adjacent, costs the same number of steps (usually one, see direction). For example, in the unordered character, 0 <-> 1 <-> 2, the transformations 0 <-> 1, 1 <-> 2 and 0 <-> 2 all cost the same number of steps. Fitch optimization uses unordered characters. Cf. ordered.
Glossary of Plant Systematics (1st ed.) by Simpson (2006)
- Referring to a character transformation series in which each character state is allowed to evolve into every other character state with equal probability, generally in a single evolutionary step.
- 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.
- Simpson, M. G. 2006. Plant Systematics. -xi + 590 pp. Elsevier Academic Press, Oxford.