Fairly large datasheet at 981 KB, in PDF, identified as SDNS040A, where the A suffix likely denotes a revised version of the document. The name does not reveal which component it describes, so confirm that from the cover page. A document of this size usually includes detailed functional descriptions, timing diagrams and package drawings, useful for probing the chip in circuit, understanding its role on the board and ensuring a replacement matches the original package.
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 @datasheet_technar_org. 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.