Small 133 KB RAR archive named only Z77-A, giving no brand, file type or revision, so its contents cannot be confirmed from the title. The name points to a board based on the Intel Z77 chipset, and the size is in line with a compressed boardview or a small set of documents rather than a full BIOS image. Open it and check which files are inside before use. Compare any board model and revision printed on the PCB against the contents before tracing rails or locating components.
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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.