1. Apparatus for generating a flow chart consisting of boxes, joined by connecting links, the apparatus comprising: A. a data processing unit; B. an input device connected to said data processing unit; and C. a display device which is also connected to said data processing unit and which has vertical and horizontal axes; the data processing unit including means for causing display on the display device of a plurality of boxes and means for accepting from the input device data identifying a starting box and an end box, the processing unit further comprising means for causing display on the display device of a connecting link between the starting box and the end box, said data processing unit also including: (a) means for defining a link start point associated with the starting box, and a link end point associated with the end box; (b) means for calculating whether first and second lines joining the link start point and respective first and second intermediate target points are obstructed by a non-permitted obstacle, said lines being parallel respectively to the horizontal and vertical axes of the display device, and having a length equal respectively to horizontal and vertical displacement of the link end point from the link start point, such that said intermediate target points may be joined to the link end point by respectively third and fourth lines parallel respectively to the vertical and horizontal axes; (c) means for determining when no such obstacle is discovered, whether the said third and fourth lines joining said intermediate target pints, and the link end point, are obstructed by non-permitted obstacles, and for generating when no obstacle is encountered to the third and fourth lines, a connecting link on the display device, composed of the first and third, or of the second and fourth said lines; (d) means for determining, when either said first and said second lines are obstructed, whether a channel exists which is not obstructed by non-permitted obstacles, said channel joining the respective first or second line, and a line parallel thereto, and displaced therefrom by respectively vertical or horizontal displacement of the link start point from the link end point; and (e) means for storing a value to indicate the first and second lines respectively to be allowable, in accordance with whether or not a corresponding channel is found to exist for said lines respectively, and means for defining a junction of the channel with the respective first or second line as a new start point, in construction of a desired connecting link.