Because the Vocabulary is organized as a tree in Corticon Studio, it may be helpful to extend the tree analogy to better understand what aliases do. The tree view permits us to use the business terms from a number of different perspectives, each perspective corresponding to one of the root-level terms and an optional set of one or more branches.

Table 1. Vocabulary Tree Views and Corresponding Branch Diagrams
Vocabulary Tree Description Branch Diagram
This portion of the Vocabulary tree can be visualized as the branch diagram shown to the right. Because this piece of the Vocabulary begins with the FlightPlan root, the branches also originate with the FlightPlan root or trunk. The FlightPlan's associated cargo and aircraft terms are branches from the trunk.

Any rule expression that uses FlightPlan, FlightPlan.cargo, or FlightPlan.aircraft is using scope from this perspective of the Vocabulary tree.
This portion of the Vocabulary tree begins with Aircraft as the root, with its associated flightPlan branching from the root. A cargo, in turn, branches from its associated flightPlan.

Any rule expression that uses Aircraft, Aircraft.flightPlan, or Aircraft.flightPlan.cargo is using scope from this perspective of the Vocabulary tree.
This portion of the Vocabulary tree begins with Cargo as the root, with its associated flightPlan branching from the root. An aircraft, in turn, branches from its associated flightPlan.

Any rule expression that uses Cargo, Cargo.flightPlan, or Cargo.flightPlan.aircraft is using scope from this perspective of the Vocabulary tree.

Scope can also be thought of as hierarchical, meaning that a rule written with scope of Aircraft applies to all root-level Aircraft data. And other rules using some piece (or branch) of the tree beginning with the root term Aircraft, including Aircraft.flightPlan and Aircraft.flightPlan.cargo, also apply to this data and its associated collections. Likewise, a rule written with the scope of Cargo.flightPlan does not apply to root-level FlightPlan data.

This provides an alternative explanation for the different behaviors between the Rulesheets in Expressing the Rule Using Root-Level Vocabulary Terms and Rule Expressed Using FlightPlan as the Rule Scope. The rules in the former are written using different root terms and therefore different scopes, whereas the rules in the latter use the same FlightPlan root and therefore share common scope.