屋外 and 室内: outdoors and indoors
Describe activity spaces in relation to the inside and outside of buildings.
Outside a building
屋外 (おくがい) refers to an outdoor space. 「屋外で運動します」 means exercising outdoors, with で marking the activity location.
「屋外用の椅子」 means a chair intended for outdoor use. It describes its purpose, not necessarily its current location.
Inside a room or building
室内 (しつない) refers to an indoor space. 「室内は暖かいです」 says that it is warm indoors, not necessarily outside.
「室内に植物を置きました」 means putting plants indoors. に marks the placement location; an original outdoor location cannot be assumed.
A change of venue
「雨の場合は室内で行います」 says the activity will be held indoors if it rains. It does not report actual rain or an already completed venue change.
「屋外では使わないでください」 prohibits outdoor use. It does not separately guarantee that indoor use is always safe; retain the stated scope of the restriction.
Does 「室内用」 give a current location or intended use?
Show the answer and why
It means intended for indoor use. The current location must be checked separately.