PDF datasheet of about 175 KB for the 2SB1555, a PNP bipolar transistor under the Japanese JIS 2SB numbering for low-frequency devices. No vendor, package or revision is mentioned in the name. In repair work the sheet is used to confirm the pinout before measuring, check collector-emitter breakdown and current ratings, and review hFE classes and the package marking. Matching these against the part fitted on the PCB helps confirm identity and choose an equivalent with suitable ratings and 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.