Catalogued among schematics, this 115 KB PDF is named simply 403DMQ, with no suffix indicating a voltage variant and no device details. The code follows the style of a power semiconductor family name, so the content likely covers several rating variants in one datasheet. Expect package outline, terminal arrangement and maximum ratings. It is handy when identifying a module in a high-current supply and finding an equivalent. Read the full marking on the component to select the right row in any variant table before ordering.
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.