REX640 PCL4 Firmware Release 1.3.6

This document is a release note detailing firmware version 1.3.6 for REX640 PCL4 protection relays and HMIs, applicable to units with PCL4 and firmware version 1.3.5 or earlier. It outlines implemented usability and operational improvements across communication, control, HMI, supervision, and protection functions, including fixes for SMV stream sender consistency, bus transfer voltage configuration, and thermal protection calculation.