Large 9.56 MB PDF identified only by a numeric name, filed as a schematic. The name gives no brand, model or board number, so the contents have to be checked by opening it. At this size it could be a full service manual or a multi-page schematic set with layouts. Once identified, compare its board numbers and revision with those printed on your PCB before using it to trace power rails, signal paths or component locations.
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 @datasheets1. 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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)