PDF documentation, 260 KB, for the 2SA1955 transistor, listed under schematics but most likely a datasheet because the name is only a part number. The 2SA prefix is the JIS code for a PNP bipolar device. Useful content typically includes terminal layout, outline drawing, maximum ratings and gain ranks, which a technician needs when testing a suspect part or matching a replacement. The file name states no manufacturer or revision, so check that the package drawn matches the one fitted.
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.