Short PDF of about 41 KB, filed as a schematic but named only with the part code 5LN01M. The code looks like a discrete semiconductor marking rather than a board number, so the document is most likely a component datasheet with pinout, package outline and electrical limits. Technicians use such sheets to confirm a replacement part's polarity, threshold and current rating before soldering. Compare the marking on the actual SMD package with the code here, since suffix letters usually denote different packages.
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.