A 179 KB PDF placed in the schematic section and named only 20TQ, with no device, board number or revision mentioned. The short code looks like a component series designation, which suggests a reference document for a family of parts rather than one board layout. Open it with any PDF viewer. A technician would use it to verify pinout, package and electrical limits when testing or replacing a part. Compare the full code on the component body against the variants listed, since suffixes usually set the rating.
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 @cyberlanelectonik. 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.