The Editor is invoked by choosing the EDITOR from the main TRIGRID menu. For the PC, a number of messages concerning loading of the DOS Extender and graphics drivers appear for a few seconds. On all platforms, a frame for the grid editing area is drawn in white on the screen and an information panel is displayed on the right. At this point, the user is prompted to enter, via the keyboard, the name of the input file (in NEIGH format) containing the grid to be edited. The initial display shows the entire grid being edited, but up to six levels of windowing (zoom) are permitted. If the grid is larger than 1000 nodes, only the outline is shown initially. The entire grid can be displayed by selecting Refresh from the main menu.
Editor options are presented to the user in menus which appear across the top of the screen, and additional prompts are displayed when necessary. Selections from the menus are made by means of the mouse, but some editing operations require keyboard input also.
The various editor options are discussed below, menu by menu. One important editor facility which should be noted is the interim save option; it is recommended that the current version of the grid should be saved at regular intervals during long editing sessions, in case of power failures or other interruptions.