/crosshotbar
　display [number] on
　　Display cross hotbar [number].
　display [number] off
　　Hide cross hotbar [number].
　display [number]
　　Toggle on/off cross hotbar [number].
But when executed, it triggers the following error message.
"display" is not a valid subcommand.

In other language versions, there is no description for "display". This subcommand is valid for /hotbar, but not for /crosshotbar.