you make a stack by dding grid to a list and then naming the output GRS file. you can remove grids from the list individually or all at once if you make a mistake or change your mind. DIVA tells you about the dimensions and location of each grid you add to the stack. these must be identical for all grids in the stack. if you forget which grids are in a stack, or wonder whether it is still valid, or why it is not, use the check stack tab to obtain a list of the grids included in a specified stack. you can edit stack files with text editors such as notepad.