PDF file of 231 KB for the 2SA1586, catalogued as a schematic but named after one discrete semiconductor. JIS part numbers starting with 2SA identify PNP transistors designed for high-frequency circuits. The sheet probably contains electrical characteristics, hFE rank letters and a package outline with pin numbering. It supports in-circuit fault finding, since the expected junction polarity tells you what a diode-mode reading should look like. Check pinout and ratings carefully before fitting any cross-referenced substitute.
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.