Covering the 2SC4636LS, this 30.6 KB PDF is likely a brief datasheet for a package variant of the 2SC4636 NPN transistor. LS is a suffix the name gives without explanation, so compare the outline with the physical part before fitting it. It is filed as a schematic, but no circuit, board or device is referenced. A technician uses it to check lead arrangement, footprint and the main voltage and current ratings when sourcing or confirming a replacement. Readable in any PDF viewer.
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.