In biology or medicine, a multi-access key is an identification key which overcomes the problem of the more traditional single-access keys (dichotomous or polytomous identification keys) of requiring a fixed sequence of identification steps. A multi-access key enables the user to freely choose the set and characteristics that are convenient to evaluate for the item to be identified. Multi-access keys may be printed in various way (tabular, matrix, formula style, etc.) but are more commonly used as computer-aided, interactive keys.