Such an encapsulation will have an associated sub-plan which is the object of the encapsulation. An entity variable allows reference to an entity without naming the specific entry. An entity variable is a virtual entity which anticipates a deferred real entity. The content of a constraint is represented by any one of a range of different constraint types. Issue which is an outstanding aim, objective, preference, task, flaw or other issue which remains to be addressed by the plan.
Issues provide implied constraints on the real world behaviour specified by the plan.
Issues are represented by a verb , zero, one or more noun phrases and zero, one or more qualifiers . Noun phrases and qualifiers are stated as expressions involving other entities associated with the planning process or plan. Other Constraint which says that one of a range of different constraints types should be satisfied in the real world behaviour specified by the plan. Include Activity and Issue constraints are separated out as they are so important to the reasoning methods normally associated with the planning and enactment processes. The rest of the constraints can be seen as further filtering the sub-space principally defined by the include activity and issue constraints.