Catalogued among schematics, this 54.5 KB PDF is named for the 2SB642, which the JIS 2SB prefix marks as a PNP transistor; the document is therefore expected to be a datasheet, and the _E ending most likely means English. Look for the package drawing, lead identification, maximum voltage and current, and gain ranks. These values are what a technician compares when sourcing a replacement for an obsolete Japanese part, along with the pin order, which is not guaranteed to match on equivalents in the same case.
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.