2008NS 3420-Z-2008 Specification tests for building,construction and installations Part Z:Operation and maintenance
2007NS 3420-CK-2007 Specification texts for building and construction Part CK:Maintenance and operation of parks and landscape
NS 3420-CK-2007 Specification texts for building and construction Part CK:Maintenance and operation of parks and landscape was changed to NS 3420-Z-2008 Specification tests for building,construction and installations Part Z:Operation and maintenance.