An order that is created by policy, and which is not tied to a single patient, but which is generated for a patient when certain conditions are met. For example, a policy might exist that persons deploying or traveling to a particular region must have a particular vaccination administered beforehand. Note that this class is a placeholder for such Standing Orders. It exists so that a Healthcare Order might be able to reference the Standing Order that caused the Healthcare Order to be created. However, details regarding what information makes up a well-formed Standing Order, or the circumstances under which a Standing Order is created, managed, invoked, or retired are not in scope for this iteration and will be fleshed out in a future interation.