RAR package of 1.76 MB for the Toshiba M500 laptop, referring to the Compal-style board number LA-2861. Compal marks its motherboards with these LA codes, typically printed on the PCB with a revision suffix. The name does not say what the archive holds; most likely it is a schematic set for tracing voltage rails, checking EC and power button signals, and locating components during board-level repair. Extract and verify the title block and board revision against your unit before taking readings from 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 @alischematics. 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.