1. A data processing system comprising: a keyboard structure for a multi-character keyboard having a plurality of keys; representation device configured for on-screen representation of said keyboard structure; selector configured for activating a particular keyboard key; and substitution device configured for selecting a first subset of keyboard keys for direct selection of a particular key by said selector and thereby presenting associated key data to said data processing system, selecting a second subset of keyboard keys for simultaneous on-screen representation with said first subset for indirect selection, and substitutively shifting said second subset in place of said first subset if user selection is of one of said second subset, wherein said second subset are first substituted by said substitution device before said second subset are directly selectable.