Schematic document in PDF form whose name, a string of numbers with R22A, does not identify the brand, model or board, so the exact device must be confirmed by opening it. Title blocks on the pages usually show the project name and revision. Once matched, a schematic serves to trace power rails, check signal paths between chips, and find component values around a faulty section. The file is 2.05 MB and opens in any PDF viewer; verify the board number printed on the PCB against the title block before working from 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 @boardview. 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.