The short name 12tq on this 179 KB PDF suggests a family-level datasheet for Schottky rectifiers in the International Rectifier or Vishay style, covering several voltage grades under one series code. It is listed as a schematic, but the contents are likely ratings tables, forward characteristic curves and package drawings. A technician would use it to identify the voltage grade of a fitted part from its suffix and to choose a correct replacement. Read the full code printed on the component first.
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.