PDF schematic for Apple logic board 820-2997, stored in an 841 KB RAR archive. The 820-xxxx number is Apple's own logic board identifier and appears printed on the PCB, which is the reliable way to confirm a match. With the circuit pages a repair technician can trace the charging and power circuitry, identify which rail is pulled down by a shorted component, and check signals between the PMU, SMC and CPU. No model name is given in the file name, so identify the machine by the board number alone.
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.