Related Rule
Australia
Practice Relating to Rule 10. Civilian Objects’ Loss of Protection from Attack
Australia’s Defence Force Manual (1994) lists among military objectives “objects, normally dedicated to civilian purposes, but which are being used for military purposes, eg a school house or home which is being used temporarily as a battalion headquarters”. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 527(i).
The manual specifies:
For this purpose, “use” does not necessarily mean occupation. For example, if enemy soldiers use a school building as shelter from attack by direct fire, then they are clearly gaining a military advantage from the school. This means the school becomes a military objective and can be attacked. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 530.
The manual also considers that “civilian aircraft, vessels, vehicles and buildings which contain combatants, military equipment or supplies” are also military objectives. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 527(e); see also Law of Armed Conflict, Commanders’ Guide, Australian Defence Force Publication, Operations Series, ADFP 37 Supplement 1 – Interim Edition, 7 March 1994, § 951.
Australia’s LOAC Manual (2006) lists among military objectives “objects, normally dedicated to civilian purposes, but which are being used for military purposes, eg a school house or home which is being used temporarily as a battalion headquarters”. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, § 5.31; see also § 9.18.
The manual specifies:
For this purpose, “use” does not necessarily mean occupation. For example, if enemy soldiers use a school building as shelter from attack by direct fire, then they are clearly gaining a military advantage from the school. This means the school becomes a military objective and can be attacked. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, § 5.34.
The manual also considers “civilian aircraft, vessels, vehicles and buildings which contain combatants, military equipment or supplies” as military objectives. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, § 5.31.
Regarding civilian aircraft, the manual further states:
Civil aircraft in flight (including state aircraft, which are not military aircraft) should not be attacked. They are presumed to be carrying civilians who may not be made the object of direct attack. If there is doubt as to the status of a civil aircraft, it should be called upon to clarify that status. If it fails to do so, or is engaged in non-civil activities, such as ferrying troops, it may be attacked. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, §§ 8.56–8.57 and 8.59.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).
Australia’s Defence Force Manual (1994) states: “In cases of doubt whether an object which is normally dedicated to civilian purposes, such as a church, is being used to make an effective contribution to military action, it should be presumed to be a civilian object.” 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 528; see also § 530 and Law of Armed Conflict, Commanders’ Guide, Australian Defence Force Publication, Operations Series, ADFP 37 Supplement 1 – Interim Edition, 7 March 1994, § 976.
Australia’s LOAC Manual (2006) states: “In cases of doubt whether objects which are normally dedicated to civilian purposes, such as a church, are being used to make an effective contribution to military action, they are presumed to be civilian objects.” 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, § 5.32.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).