Reference sheet for the 2N5457, a general-purpose N-channel junction field-effect transistor, saved as a 130 KB PDF. No manufacturer or document revision appears in the name. A repair technician uses it to read the package outline, identify drain, source and gate leads, and compare limits before substituting a part such as a 2N5458. Any PDF viewer will open it. Confirm the lead order against the actual component, because TO-92 JFETs from different vendors do not always share the same pinout.
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.