PDF datasheet of 131 KB describing the PC4002LRS-BSO-B alphanumeric display. The part code points to a 40 character by 2 line LCD, with BSO-B marking a specific option set and revision B, distinct from the CSO version. Typical contents include pin functions, electrical ratings, backlight data, timing diagrams for the parallel interface and a dimension drawing. It helps when checking contrast voltage on a dim screen or wiring a substitute module. Make sure the label on your part reads the same suffix before relying on backlight or voltage figures.
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.