<Control Links> and <Variables> in Practice
Since a <Control Link> always uses an <Expression> containing a <Variable>, <Control Links> are only used within <Models> and <Environment Roots>.
The <Interface Template> component of a <Model> has ordered 1-way associations to every <Variable> within that <Model>.
- The user doesn’t have to search the <Model> to find all the <Variables>
- Lock-and-key analogy: The <Interface Template> defines the ‘lock’ - all the <Variables> that must have values plugged in. The model instances must provide the ‘key’ - the <Expressions> to be plugged into those <Variables>.