Property Order Selection Types represent a way of, when using criterias to order annotations in agendas, and having more than one property of a specific type in a single annotation, selecting which of the properties to use when comparing the given annotation with the others to place it in order.
Thus, possibilities for Property Order Selection Type includes "HIGHEST" to select the "highest" property by the given order when ordering, or "LOWEST" to select the lowest. Intermediate options are not available.