Related Rule
Australia
Practice Relating to Rule 7. The Principle of Distinction between Civilian Objects and Military Objectives
Section A. The principle of distinction
Australia’s Defence Force Manual (1994) provides:
210. Although not a basic principle, distinction is said to be a related principle and seeks to ensure that only legitimate military objects are attacked. Distinction has two components. The first, relating to personnel, seeks to maintain the distinction between combatants and non-combatants or civilian and military personnel. The second component distinguishes between legitimate military targets and civilian objects.
504. The law of armed conflict establishes a requirement to distinguish between combatants and civilians, and between military objectives and civilian objects. This requirement imposes obligations on all parties to a conflict to establish and maintain the distinction. …
913. The basic rule in respect of civilians which flows from this is that a distinction must be made between the civilian population and combatants, and between civilian objects and military objectives, in order that military operations will only be directed against military objectives. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, §§ 210, 504 and 913.
Australia’s LOAC Manual (2006) states:
2.11 Although not a basic principle, distinction is said to be a related principle and seeks to ensure that only legitimate military objects are attacked. Distinction has two components. The first, relating to personnel, seeks to maintain the distinction between combatants and non-combatants or civilian and military personnel. The second component distinguishes between legitimate military targets and civilian objects. Military operations must only be conducted against military objectives, including combatants. Non-combatants and civilian objects are protected from attack, that is, they are not legitimate objects of attack. LOAC therefore requires that belligerents maintain the clear distinction between armed forces and civilians taking no direct part in hostilities; that is, between combatants and non-combatants, and between objects that might legitimately be attacked and those protected from attack.
5.4. The LOAC establishes a requirement to distinguish between combatants and civilians, and between military objectives and civilian objects. This requirement imposes obligations on all parties to a conflict to establish and maintain the distinction …
9.13. … a distinction must be made between the civilian population and combatants, and between civilian objects and military objectives, in order that military operations will only be directed against military objectives. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, §§ 2.11, 5.4 and 9.13.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).