PC1602LRU-FSO-H datasheet, a 137 KB PDF for a character LCD module that the 1602 code marks as 16 characters by 2 lines. The FSO-H letters denote the specific option build. Such sheets usually include interface pinout, maximum ratings, operating voltages, backlight characteristics and an outline drawing with hole positions. Technicians consult them to measure the correct rails, troubleshoot contrast or backlight faults and verify that a substitute module matches mechanically and electrically.
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.