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Tunic
A vestibule is a transitional space between doors intended to protect against the penetration of cold air, smoke, and odors when entering a building, stairwell, or other rooms (Appendix No. 1 mandatory, SNiP 2.08.01-89*)
Source: Order of the Ministry of Regional Development of Russia dated August 4, 1998 No. 37 (as amended on September 4, 2000) "On Approval of Instructions for Conducting Housing Stock Accounting in the Russian Federation" (with amendments and additions coming into force on May 19, 2008)