PDF schematic for a board designated Z65, about 1.57 MB, with nothing else in the name to indicate brand, model or revision. Treat it as a reference circuit diagram for that board code: power rails, voltage regulators, clock and reset logic, and interface connectors are the usual contents. Technicians rely on such files when hunting a short, confirming which component feeds a rail, or reading expected voltages. Any PDF program can display it. Before working from it, verify that the number printed on the PCB is Z65 and note any revision marking there.
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.