Specification sheet in PDF for the PC1602LRS-GSO-H-P2 display, a 16 characters by 2 lines LCD according to standard 1602 numbering. GSO-H-P2 identifies the variant and document version. Usually such sheets give header pinout, electrical ratings, contrast and backlight data, timing and outline drawings. On the bench it serves for checking supply, contrast and backlight lines on a failing module, and for confirming that a substitute matches both electrically and mechanically before installation.
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.