As to the sources of ius in interregno, both stable and evolving norms applicable to TG should be considered. Individual customary rules are germinating in relation to TG but not in isolation from the existing principles of self-determination and non-intervention. As to the evolving part of ius in interregno, TI may testify to the emergence of custom. Both domestic laws, unilateral declarations, intrastate agreements or international conventions can be taken into account. Socialisation explains why these and other instruments incorporate TG-relevant patterns. The effects of dominant discourse and mimesis entice a common (legal) culture accounting for both the (socialised) origin of, and (legal) compliance with, specific behavioural patterns. This fertile breeding ground also explains why such patterns are formalised through the adoption of TI, which may or may not be valid on the domestic plane: compliance with international law is expected regardless of how the transition was triggered.