Lowercase terms are non-terminal.
Parentheses specify scope.
Elements within brackets are optional. Main structure of the proposed grammar for objectives. Arrows indicate types of fillers for one element of the grammar. The idea is to distinguish an objective that involves a target from the target itself, thus allowing e.g. the representation of support missions. Air Missions were tentatively included at SRI's request, representing a special type of Air Activity that is generally fulfilled by a group of homogenous aircraft.