PDF for the IRF540 MOSFET, and the name indicates the datasheet comes from Philips. Although listed under schematics, the 91.6 KB file is a component sheet with ratings, characteristic curves and pinout for the TO-220 package. Technicians refer to it when checking a suspect transistor, identifying legs for meter testing, or comparing a substitute from another manufacturer. Since each maker specifies its version slightly differently, confirm the actual brand on the part and compare voltage, current and on-resistance before swapping.
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.