Small PDF of 27.3 KB for the 3LN01N, catalogued as a schematic though the name reads as a discrete transistor part number, so it is most likely a datasheet. The file name carries no device or board information beyond that code, and related entries 3LN01M and 3LN01C point to variants of the same base part, likely in different packages. Technicians use it to check pinout, ratings and package outline before replacing a small-signal transistor. Open it in any PDF viewer and confirm the package and marking match.
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.