1. A method comprising: assigning a value to a first token in a description, the value indicating either: that the first token also occurs in a header of the description, that a lexical association exists between the first token and a second token in the header, or that the lexical association does not exist and the first token is absent from the header; computing a relevance value of a group of tokens that occur in the description and include the first token with the assigned value, the relevance value of the group being computed by a processor of a machine based on the value assigned to the first token; indicating that the group of tokens is a most relevant group of tokens in the description; wherein: the assigning of the value to the first token includes initially assigning a default value that indicates the lexical association does not exist and the first token is absent from the header; and the assigning of the value to the first token includes overwriting the initially assigned default value based on the first token occurring in the header.