To obtain a reasonably valid phylogeny, the researchers found they needed to enter as input all three types of characters: phonological, lexical and morphological, which were all required to present a picture that was sufficiently detailed for calculation of phylogeny. Only qualitative characters produced meaningful results. Repeated states were too ambiguous to be correctly interpreted by the software; therefore characters that were subject to back formation and parallel development, which reverted a character to a prior state or adopted a state that evolved in another character, respectively, were screened from the input dataset.