Likely part of the software version or manufacturer code.
Finding these .rar files usually requires visiting specialized technician forums or firmware databases. Because these files are hardware-specific, (make it unusable). Common Sources for LED TV Firmware: Kazmi Elecom : A popular site for universal board software. Download ATM20 PB819 1366x768 REF35 rar
: If possible, use a programmer (like the RT809F or CH341A) to save your current firmware before flashing a new one. Likely part of the software version or manufacturer code