Keys are divided into different key-groups. The Criteri-R key-group targets the Criteri-R app. The User key-group allows users to define their desired key texts like macros. Alphabets and General punctuations and symbols are added for normal inputs. Besides the common math input keys, on the keyboard there are a number of mutable keys whose contents can be changed to map to any keys in the selected key-group. Users can define as many keys as they need in the User key-group. In this way, M