PDF schematic for the Samsung SGH-2100 mobile phone, about 952 KB, marked with the smdmobile.ir watermark. Service schematics of this kind show the power supply, charging circuit, RF, audio and keypad sections. They are used to trace rails, find components and check where a short sits on the board. Any PDF reader opens it. Older documents may be scanned with low resolution, so zoom carefully. Check the hardware version on the PCB, as revisions of the same phone can differ in parts.
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.