Multi-entry key

In biology or medicine, a multi-entry key is an identification key that allows the free choice of characters only in the first step. Whereas in a typical multi-access key the choice of characters used for identification can be repeated multiple times (reducing the number of remaining taxa each time), in literally multi-entry keys only the first step involves a free choice of characters. Examples for multi-entry keys are the keys created by the FRIDA software, where a single step of selecting one or multiple criteria is followed by a dichotomous key for the species remaining after this step.