Schematic document in PDF format, about 1.80 MB, filed under the name TAS6534, which looks like a Texas Instruments part number from the TAS automotive class-D audio amplifier family, although the name gives no device or board details beyond that. A technician would use it to follow the amplifier stage, supply pins, output filter and control lines when tracing a dead or distorted audio channel. Any PDF reader opens it. Confirm the chip marking on the board matches before relying on pinouts or reference values taken from this sheet.
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 @datasheets1. 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.