A short PDF specification, 67 KB, for the PG12856 graphic LCD module family, revision or variant A according to the name. Documents like this usually give the mechanical drawing, interface pin list, absolute maximum ratings and basic timing for the controller bus. It is handy when repairing instruments or control panels that use the module, for checking power and contrast lines with a meter or matching a replacement. Because the base sheet may not cover every suffix option, verify backlight and temperature variant against the actual part.
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.