At 160 KB, this PDF for the 2SB1667 is larger than the other 2SB166x and 167x sheets, perhaps containing more curves or pages. The 2SB prefix marks a PNP transistor under JIS numbering, so despite the schematic label it should be a datasheet. It should list pinout, package outline, voltage and current limits, dissipation and hFE ranks. Technicians use it to identify leads for meter testing and to verify that a substitute PNP part matches or exceeds the original ratings.
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.