6. An interface system according to claim 5 , wherein a configuration means is provided to allow a user to selectively enable or disable physical interactivity reduction characteristics of the interface system which facilitate a further reduction in the number of key presses required to create a given data string.
6. An interface system according to claim 5 , wherein a configuration means is provided to allow a user to selectively enable or disable physical interactivity reduction characteristics of the interface system which facilitate a further reduction in the number of key presses required to create a given data string. 7. An interface system according to claim 6 , wherein the physical interactivity reduction characteristics are selectable from the group comprising: (i) entering a space after selection of a data string; (ii) limitation of displayed data strings to those having a total number of characters greater than a number of key presses; (iii) expanding typed or selected mnemonics, abbreviations or acronyms into their corresponding full data strings; (iv) performing two-way translations between data strings and user-configurable dictionary definitions or descriptions; (v) enabling the selection of a secondary key-value or key-function by means of double-pressing a data input key; (vi) enabling the selection from a list of different data strings stored within the data storage by means of double-pressing a data input key, said data string having an initial letter or letters corresponding to the key-value of that key; and (vii) enabling the right-to-left and/or left-to-right deletion of n characters, words, sentences or paragraphs by means of a single key press.