An enumerated chromosome is a string of genes whose values are alleles (tokens).  Enumerated chromosomes are used in the optimization of combinatorial problems, where a problem parameter can be represented as

a sequence or combination of tokens.  All possible token values form the alphabet of an enumerated chromosome.  The fitness function in the case of an enumerated chromosome depends on the order of alleles in the gene.  The main aim of the genetic algorithm search is to find the optimum sequence of alleles of the enumerated chromosome.