A 130 KB PDF bearing the part number 2N5459, catalogued as a schematic though no board, device or revision is named. The JEDEC 2N numbering marks a discrete semiconductor, so the document is most likely a datasheet with pin diagram, package outline and characteristic tables. A technician would use it to identify leads before probing, confirm ratings and judge replacement options. Different manufacturers publish their own versions, so check the component marking and package before relying on specific values.
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.