Indexed as a schematic, this PDF of about 187 KB is named 8ETH06. In International Rectifier and Vishay numbering the ETH family is a hyperfast rectifier line, so the file should be a datasheet with voltage and current limits, reverse recovery figures and package drawing. It is useful when a diode in a PFC or flyback stage of a power supply fails. Choose a replacement with matching recovery time, not only voltage rating, and confirm the printed marking on the original part 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.