The 2N3903 with an RE suffix is documented in this 213 KB PDF; the suffix is not explained and may denote a revised or alternate edition. Placed under the schematic category, it is expected to be a component datasheet with pin configuration, package drawing and electrical ratings. Technicians use these details to test the part, assess failures and choose replacements. Several 2N3903 files exist in this collection, so cross-checking them is worthwhile when values or package information appear to differ.
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.