A 1.26 MB PDF datasheet for the UG-2828GCEAF02 display module, with a version-style tail of 1_1 in the name that may indicate a document revision. Display module specs of this size normally include interface pinout, power sequencing, driver command overview and mechanical drawings. Technicians use it to check supply rails on the flex connector, verify the power-on order, and wire up a replacement correctly. Several near-identical copies exist in this set, so compare page revision dates and pick the most recent one.
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.