Motherboard schematic in PDF format for the board code Z84J. The name carries nothing more, so the brand, model and revision are unknown and must be confirmed from the PCB. At 2.56 MB it probably covers the full set of sheets: power supply, CPU, memory, display and I/O sections. Technicians use such diagrams to trace rails, find the components behind a short, and read the expected voltages at test points. Open it in a standard PDF reader and match the board marking, since related Z84 variants share a similar but not identical design.
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 @CLRINDORE. 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.