PDF document of 132 KB for the HCF4093, the ST version of the 4093 quad two-input NAND gate with Schmitt-trigger inputs. Although listed as a schematic, it is most likely the component datasheet showing the pinout, internal gate diagram and electrical limits. Repair technicians use such a sheet to identify pins on a board, confirm that inputs switch at the expected thresholds, and check compatibility with CD4093 or HEF4093 parts, which generally share the same footprint and function.
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.