DEVICE AND METHOD FOR SPECIFYING DRAWING ALTERATION PLACE, AND COMPUTER-READABLE STORAGE MEDIUM

PROBLEM TO BE SOLVED: To specify places of alterations from an original drawing even when plural corrected drawings having mutually different alteration places are compared with the original drawing. SOLUTION: Management numbers 1 to N are given to all element figures of original data and managed together with a maximum management number N. For corrected data A, the management numbers 2, 3, 4, 7, 8, 9... of element figures deleted from the original data are deleted from a management number table, an element figure added to the original element data is added behind N+1, and a maximum management number P is held. Even for corrected data B, a maximum management number is held and figures N+1 to Q are added to be element figures. Then the two pieces A and B of corrected data are put together, and figures added to or deleted from the corrected data A, figures added to or deleted from the corrected data B, and figures which are common to the pieces A and B of corrected data (unaltered figure) are extracted according to the respective management numbers and maximum management numbers and displayed on a screen by luminance and colors.