Part number 1T409 is the only information in the name of this 49.5 KB PDF, which is catalogued as a schematic. No equipment model, manufacturer or board revision is stated. A file this small usually holds a few pages of component data, such as a pin diagram, characteristic curves and limit values. Repair technicians use that kind of sheet to identify a part, check whether a measured value is plausible, and choose a replacement. Compare the package and marking on the board with the drawing first.
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.