Compact 38 KB PDF named for the 2SC5380 transistor. The 2SC numbering marks an NPN device under the Japanese JIS scheme; the name gives no manufacturer or application. The content is most likely a short datasheet with maximum ratings, electrical characteristics and pin layout rather than a circuit diagram. It helps when testing a suspect device in circuit, confirming which leg is base or collector, and selecting a substitute whose voltage, current and frequency figures are at least equal to the original.
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.