Abstract: Data modification and display apparatus for use in a digital computer system together with a method employing data modification and display apparatus for modifying and displaying data. The data modification and display apparatus has a memory containing buffer sections for storing data codes representing data to be modified, control data including a state value for controlling modification and display of data, an editing table containing editing instruction sequences for modifying the contents of the buffer, modifying the control data, and producing display codes, a terminal with a keyboard for providing input codes and a screen for displaying visual representations in response to display codes, and a processor. Editing instruction sequences are divided into sections corresponding to certain state values and editing instructions include instructions to which the processor responds by altering state value.