1DV DR Modification of Clause 1 to replace with the following: This standard specifies alternative requirements for construction@ test and marking for electrical equipmentmounted across a boundary where different Equipment Protection Levels may be required. EXAMPLE: Equipment installed in the wall of a storage vessel containing Zone 0 (requiring EPL Ga) inside an area defined as Zone 1 (requiring EPL Gb). This standard supplements and modifies the general requirements ofUL 60079-0. Where a requirement of this standard conflicts with a requirement of UL 60079-0@ the requirement of this standard takes precedence. Where references are made to IEC 60079 standards@ the referenced requirements found in these standards shall apply as modified by any applicable U.S. National Differences.