For the guarantee of retrieval ratio, thesaurus's maintenance for descriptors are necessary. To maintain the optimum scale of thesaurus, new terms and existing terms should be structured to the equivalence relationship. Therefore, equivalence relationships are needed to new standard. This study proposes new standard of the equivalence relationships, which is more specified for better guarantee of retrieval ratios. The relationships have seven facets. These six facets will be used as new knowledge-base, which could be reestablished between the descriptors.