Final answer:
The reference for tactical doctrine in the Air Force's airpower doctrine is 'Tactical Doctrine.' It is focused on the application of airpower at the tactical level and emphasizes the importance of tactical adaptability and situational awareness.
Step-by-step explanation:
The reference for tactical doctrine in the Air Force's airpower doctrine is the Tactical Doctrine. This type of doctrine provides guidance on the application of airpower at the tactical level of warfare and includes the specific techniques and procedures for conducting military operations.
The excepts provided offer insight into the importance of understanding tactical variation, as it states: 'The general who thoroughly understands the advantages that accompany variation of tactics knows how to handle his troops.' It suggests that tactical adaptability is crucial for making effective decisions in the field. This aligns with the principle that the tactical doctrine is the foundation for how specific military engagements are to be conducted.
The reference to not following certain roads, attacking specific armies, or besieging towns indicates situational awareness and choosing the correct tactic based on the scenario, which is a primary focus of tactical doctrine.