Base datasheet for the 25tts series, saved as a 232 KB PDF and catalogued as a schematic. The name is a power semiconductor part code with no manufacturer, device or board stated. Such documents give blocking voltage, on-state current, gate trigger characteristics where relevant, surge ratings and package information. Repair technicians use them to test a shorted or open device in mains-side circuits and choose a correct replacement. Check the full marking, including any suffix, on the component before ordering parts.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @cyberlanelectonik. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.