Predicate names are arbitary strings of small and capital letters, the numbers 0-9 and dashes. We adopt the unique name assumption, i.e., different variables stand for different objects in the world. Everything that is deleted by the operator has to be mentioned explicitly, i.e., our operators do not automatically delete their preconditions. There can be a possibly infinite number of different conditional effects, which can be empty. The implication sign can be dropped in conditional effects.
Operators can have empty paramaterlists, preconditions and effects.
Names should not be longer than 256 characters. The syntax still admits it, but it makes no sense for the planner. Equality and Disequality should never occur in effects.