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. DOB indicates the direct object. In practice, an interface that produces a human readable version of an objective migt prefer to ommit this token, which is necessary only for machine parsing purposes. This is intentional, as a way to preserve the ability of the users to define objectives beyond the limits of the defined grammar.