Reference PDF of 598 KB for the CD4042BE, a CMOS quad clocked D latch in the 4000 series; the E suffix usually indicates the plastic DIP package. Filed as a schematic, the content is likely the manufacturer datasheet with pinout, truth table and timing data. A technician uses it to check clock and polarity inputs, confirm latched outputs and their complements with a probe, and verify that a replacement part from another maker shares the same pin arrangement and ratings.
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.