Second copy of the M9A0 MP schematic, a 945 KB PDF that is slightly larger than the other file with the same code and may therefore carry a different revision or extra pages. MP stands for Mass Production, the final released design stage. The brand and device are not given, so check the title block and revision history. A schematic like this supports tracing rails, signals and component references; make sure the board number and revision on the PCB match the version you use.
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 @cyberlanelectonik. 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.