PDF named RTS545X, which refers to a Realtek RTS545x series chip, commonly a USB Type-C power delivery controller; the name gives no board or device. Filed as a schematic, it likely shows reference circuitry or pinout for the controller. Technicians use such material to check supply pins, I2C lines and CC signals when a laptop will not charge over Type-C. Open it in any PDF reader and match the exact chip marking on your board before relying on pin numbers.
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 @sm_bios. 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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)