Datasheet for the PC2004LRU-MEA-B alphanumeric display module, a 135 KB PDF. Under the usual convention it is a 20 character by 4 line LCD, one of the most common character formats, and MEA-B fixes the option set and revision. It contains the pinout, controller command set, signal timing, supply and contrast specifications and the outline drawing. Repairers rely on such sheets to confirm the parallel interface wiring or to identify a drop-in substitute. Check the module sticker for the same suffix before using backlight or voltage values.
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.