Sony M870 archive for motherboard MBX-214 at revision 1.0, 1.46 MB in RAR format. This appears to be the original copy, while a separate decrypted edition also exists, so the PDF inside may be password protected against editing or printing. The contents are useful for tracing power sequencing, checking the voltage regulators and finding test points on a VAIO board. Sony uses the MBX-xxx code silkscreened on the PCB, and that code plus the revision should be confirmed before working from the drawings.
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 @generalschematics. 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.