Compressed RAR archive of 130 KB labelled DLS XM40, with no indication in the name of whether it holds a schematic, boardview or firmware dump. DLS is commonly a car audio brand, but the name confirms nothing about the device or board. Extract it and inspect the contents before use: identify the file types inside, compare any part numbers or revisions with the hardware on your bench, and if a firmware image is present, back up the original memory chip with a programmer before writing anything to 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 @schematicslaptop. 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.