The 2SA1621 is covered by this 194 KB PDF, listed among schematics but really describing one discrete semiconductor. In JIS nomenclature the 2SA prefix marks a PNP transistor for high-frequency applications. The name gives no maker or revision. A technician would consult it to verify the package marking and pin assignment when testing the part in circuit with a multimeter in diode mode, and to compare collector current, voltage and power limits when looking for an equivalent replacement.
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.