A new list of forbidden items was made up that included bombs, explosives (or material for their manufacture); signal devices, codes or ciphers; papers, documents or books with invisible writing; photographs, sketches, pictures, drawings, maps, or any graphical representations of military or naval installations or equipment, or of arms, ammunition or implements of war that could be used in combat situations. This list applied to enemy aliens.

Enemy Aliens Must Turn In Explosives, All Codes

1900.5282