images,s,a,,,,images to be edited
fields,s,a,,,,fields to be edited
value,s,a,,,,value expression
add,b,h,no,,,add rather than edit fields
addonly,b,h,no,,,add only if field does not exist
delete,b,h,no,,,delete rather than edit fields
verify,b,h,yes,,,verify each edit operation
show,b,h,yes,,,print record of each edit operation
update,b,h,yes,,,enable updating of the image header