Small 329 KB PDF titled OZ9906, with no further detail in the name. The OZ prefix is used by O2Micro, whose ICs often appear in LCD backlight and inverter circuits, so the file is likely a datasheet or reference design for that part. Use it to look up pin functions, operating voltages and the recommended external components when diagnosing a backlight or power fault. Any PDF reader opens it. Confirm that the marking on the chip in front of you matches OZ9906 before relying on the values.
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 @datasheets1. 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.