This standard establishes physical characteristics and technical criteria for Synchronous Optical NETwork (SONET) interfaces, at standard rates, associated with the Network Interface (NI) for electrical interface applications. Criteria covered herein include SONET Physical Media Dependent (PMD) criteria (such as electrical parameters and connectors), and other necessary criteria for compliance with the electrical specification at the NI and the proper interfacing of the connecting customer installation equipment. Compliance with this standard is intended to ensure compatibility at the SONET NI and should not be construed as a constraint on the internal operations of the network or customer installation equipment. The provisions of this standard are intended to be consistent with applicable requirements concerning safety and environmental conditions.