Transistor 2SC4458 is the subject of this 103 KB PDF, which the catalogue lists as a schematic. Japanese JIS numbering assigns the 2SC prefix to NPN devices intended for high-frequency work, making the document a probable manufacturer datasheet. The file name gives nothing beyond the part code. Useful content typically includes absolute maximum ratings, gain groups, transition frequency and a dimensioned package drawing, all of which matter when matching a substitute or confirming the correct pinout during board repair.
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.