State immunity — Jurisdictional immunity — Building contract — Alteration work to buildings owned by foreign State — Whether foreign State entitled to jurisdictional immunity — Whether conclusion of contract for such work a sovereign or commercial activity

State immunity — Attachment and execution — Criteria for determining which assets immune from execution — Assets designated for sovereign tasks — Buildings operated by Institute of Emigration of foreign State — Use of buildings as cultural, educational and social centre for foreign workers — Whether such use relates to the exercise of sovereign powers — Whether such buildings immune from execution — The law of Switzerland