PDF of 129 KB titled 27C16, filed as a schematic but corresponding to an early member of the 27C EPROM family by its part number. The name does not identify any manufacturer, board or device. Useful data in such a sheet covers pinout, power requirements, programming pulse and voltage specifications, and erase guidelines. Those are essential when servicing vintage equipment that stores firmware on this kind of chip. Old EPROMs often need specific programming voltages, so check them carefully before writing.
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.