The 1N5394 diode is documented in this 42.7 KB PDF, listed under schematics but in practice a component datasheet. Expect the usual sections: absolute maximum ratings, electrical characteristics, typical curves and a mechanical drawing. These details matter when you test a diode in circuit, decide whether a reading indicates failure, or source a replacement. Any PDF reader opens it. Substitutes should match or exceed the reverse voltage and current ratings, and the package must physically suit the board.
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.