The -ImageDataHash option seems to be missing from the documentation... Please add it, thanks!
ImageDataHash isn't an option, it's a tag, and appears on the Extra Tags page (https://exiftool.org/TagNames/Extra.html).
Tags can be copied to other tags. Options control how exiftool operates.
Related: XMP ExifTool Tags (https://exiftool.org/TagNames/XMP.html#ExifTool)
I see, thank you! I did search in the ExifTool Tag Names (https://exiftool.org/TagNames/index.html) page, in addition to the main "Application Documentation" page, but hadn't realized that it only listed links to sub-pages. A search option for all of documentation pages would surely be useful...