according related regulations turkey four levels document classification ref name tr ref '' ok gizli'' top secret ''gizli'' secret '' zel'' confidential ''hizmete zel'' restricted fifth inscription ''tasnif '' means unclassified united kingdom security classifications uk united kingdom used five levels classification lowest highest protect restricted confidential secret top secret formerly secret cabinet office provides guidance protect information including security clearances required personnel staff may required sign confirm understanding acceptance official
Applied science Library and museum studies Classification Security classification