PDF datasheet, around 525 KB, for the PE12864BRF-007-B display module, probably a 128 x 64 dot graphic LCD given the 12864 code, with 007-B marking the build and revision. Larger sheets like this often include controller instruction tables, timing diagrams, optical curves and full outline drawings. It is useful when driving the panel from a microcontroller, checking bias voltages on a faulty unit or confirming that a replacement module shares the same connector and footprint.
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.