Reference PDF for the CD4094, an eight-stage shift-and-store bus register from the CMOS 4000 series, as the name notes it is a shift register. At 72.1 KB it most likely holds the pinout, logic diagram and timing information. Technicians use it to follow data, clock and strobe lines, confirm the output-enable state, and probe the serial chain when display or relay drivers misbehave. HEF4094 and HCF4094 parts generally share the same pin functions for replacement.
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.
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The standard format for schematics, block diagrams, power-sequence charts and service manuals.