PC4002LRS-CSO-B datasheet, a 131 KB PDF for a character LCD module. In this numbering the digits indicate 40 characters on 2 lines, and the CSO-B tail picks a particular backlight, polarizer and revision combination. The document should give the 14 or 16 pin interface assignment, controller instruction set, power and contrast requirements and outline dimensions. Repair technicians use it to confirm wiring, test a module on the bench, or find an equivalent replacement. Compare the full code on the module, as sibling variants such as BSO differ in options.
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 @acodis_lcd_datasheets_EDID. 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.