Related Rule
Practice Relating to Rule 37. Open Towns and Non-Defended Localities
Section B. Establishment of non-defended localities
Ukraine’s IHL Manual (2004) states:
“Non-defended localities” means any locality or inhabited place near or in a zone where armed forces are in contact which is open for occupation by an adverse Party.
All military objectives must be evacuated from a non-defended locality. Acts of hostility in such localities shall be prohibited.
Unlike demilitarized zones (created by mutual consent of the parties to the armed conflict), non-defended localities may be established by a unilateral declaration which shall be addressed to the adverse party (the latter shall acknowledge the receipt of such declaration). 
Ukraine, Manual on the Application of IHL Rules, Ministry of Defence, 11 September 2004, § 1.2.50; see also § 1.2.51.