A 477 KB PDF for the 2SC5087 part, an NPN bipolar transistor by its Japanese 2SC designation. Listed under schematics, its content is most likely the datasheet, and the name gives no further detail such as manufacturer or package. Open it in any PDF viewer to read electrical characteristics, maximum ratings and the lead arrangement. Useful when a transistor tests open or shorted and an exact or equivalent replacement is needed; always confirm the package and pin order against the board footprint first.
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.