Archive labelled for the HP TouchSmart 300 all-in-one, a 734 KB RAR whose name does not say what is inside, so it may hold a schematic, boardview or firmware image. No board number or revision is given, which means you should extract it and inspect the contents before relying on it. If it holds a BIOS dump, read and back up the original SPI chip with a programmer first and check that the image size matches the chip capacity. If it holds diagrams, compare the board markings on the actual PCB with those in the document.
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 @hrtechno. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.