The 2N4401 is the sole detail in this 92.7 KB PDF name; it is filed under schematics but is expected to be a datasheet for that JEDEC-registered part. Technicians use it to confirm the pinout, voltage and current ratings and gain characteristics when diagnosing a stage or selecting a substitute. It opens in any standard PDF reader. Check the package style and lead sequence against the device fitted on the board, as manufacturers may differ.
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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)