Intel SPI Programming Guide in PDF form, 913 KB, catalogued under schematics although it is a reference document rather than a board diagram. A guide of this kind explains how the SPI flash interface is organised on Intel platforms, including the flash descriptor, regions such as BIOS and ME, and access rules. It helps a technician understand why a dump must match the chip, why ME regions get cleaned, and how descriptor locks affect software flashing compared to an external hardware programmer.
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 @lappysan. 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.