The 2SA1091 is covered by this 334 KB PDF, the largest of this group, filed in the schematic category. In the JIS numbering system, 2SA indicates a PNP bipolar transistor. The file name gives only the part number; details such as package and maker are inside. Technicians use the datasheet to read maximum voltages, current, gain and pin arrangement, which is essential when choosing an equivalent for an obsolete part or checking whether a substitute fits the original footprint.
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.