Global vs. Local Objectives
Each activity has its own set of learning objectives defined for it called “local” objectives. Each activity has these by default, no explicit association to objectives is needed. The Content Developer can associate objectives to acitivities by defining them in the activity tree (via the Content Package Manifest). All objectives defined for an activity (explicitly or by default) are local to the activity. This means that the activity is aware they exist and only that activity’s SCO can affect them.
A local activity can be defined as a "global" objective. This global objective then can be shared with other learning activities. If an objective is declared to be global (via XML in the Content Package Manifest), then the Tracking Model Elements associated with the objecitive are available to other learning activities that share that same "global" objective.