ECOTONE, a new definition of ecological field, was approved by the plenary session of Ⅶ SCOPE in 1988 (Budapest). In order to have a better understanding attributions, connotations, and significations of the term, we have already provided a systematic description and logical induction. In this article, the author would use the ecological boundary theory and the technique of information measure to develop the Index Series which can be applied to determine the basic properties of ECOTONE. Generally, these ind...