A 289 KB PDF covering the 2N5172, a JEDEC-registered discrete semiconductor, catalogued as a schematic though the name points to a manufacturer datasheet. Nothing else about the source or revision appears in the name. Typical use at the bench is checking the lead order, absolute maximum ratings and gain or switching characteristics when sourcing a substitute. Verify that the package and pin assignment in the document match the physical part, since different makers sometimes use different lead arrangements.
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.