The 155 KB PDF titled 15tq060 is listed under schematics, but the name corresponds to the International Rectifier and Vishay Schottky rectifier numbering style. It is most likely the datasheet for that diode, with absolute maximum ratings, forward voltage curves and the package outline. Technicians consult it to verify that a replacement has adequate voltage and current margin, or to make sense of diode-mode meter readings. Make sure the printed part code on the board matches before using it.
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.