PDF of 47.7 KB named 2PD602A, apparently issue 4 of the document. The name identifies a part rather than a product or board, which points to a discrete semiconductor data sheet with ratings tables and characteristic curves. It sits next to the closely numbered 2PD601A sheet, so do not mix them up when ordering. A technician reads such a file to confirm polarity and pin assignment, check voltage and current limits, and decode SMD marking codes. Any PDF reader opens it; verify the package on the board 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.