Service schematic in PDF form for the Nokia X6, covering the RM-551 and RM-559 variants, about 3.74 MB in size. Phone schematics like this are used to follow power rails from the PMIC, trace signal paths between the baseband and peripherals, and locate components when diagnosing shorts or no-power faults. Any PDF reader opens it, and searching component designators speeds up lookups. Confirm which RM variant your handset is, since the two type codes may differ in parts of the circuitry.
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 @mobileshematic. 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.