The 2SA1012 PNP bipolar transistor, so identified by its JIS 2SA prefix, is documented in this 216 KB PDF. The file name gives no manufacturer, so the source should be checked in the document itself. Contents typically cover maximum voltage and current ratings, power dissipation, gain grades and package outline. A technician uses it to identify pin functions before testing, to confirm whether a measured value is out of spec, and to choose a suitable substitute for a damaged part.
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.
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The standard format for schematics, block diagrams, power-sequence charts and service manuals.