Skeleton in an earlier thread,
Fishead had this to say
From the "Rules concerning the Control of Wireless Telegraphy in Time of War and Air Warfare. "
Part II, Chapter 1, Article 3 states:
quote:
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Art. 3. A military aircraft must carry an exterior mark indicating its nationality and its military character.
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further articles go on to say:
quote:
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Art. 7. The exterior marks required by the above articles shall be affixed in such manner as to make it impossible for them to be altered during flight. They shall be as large as possible and shall be visible from above, from below and from either side.
Art. 8. The exterior marks required by the regulations in force in each State shall be brought without delay to the knowledge of all the other Powers.
Modifications made in time of peace in the regulations requiring exterior marks shall be brought to the knowledge of all the other Powers before being put in force.
Modifications made in such regulations at the outbreak or in course of hostilities shall be brought by each Power to the knowledge of all the other Powers as soon as possible and at the latest when they are communicated to its fighting forces.
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Link to ICRC document
This comes under the definition of 'Hague Law' and so is 'Customary International Law', rather than being codifed...