PDF of 268 KB named 25tts-s, listed as a schematic, with a name that resembles a power semiconductor series designation. The -S ending likely refers to a package or version variant, but the file name does not explain it. No manufacturer, device or board is given. Expect ratings, characteristic curves and package drawings. Those let a technician verify a suspect thyristor or rectifier in a power stage and pick a replacement. Compare the code on the component body with this sheet before substituting.
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.