This display element is used to display a number on the screen
in percents (e.g. 0.7 will be displayed as 70%,
compare with Number Display).
Note that this display element should be used only when the user
is not expected to change the displayed number interactively ("read only" mode).
To allow the user to edit a number, use
Number Input Field.
<Value> (non-repetitive number element): The displayed number.
Access it (to set it for display or to retrieve the number that has been
displayed) through a reference to the parent Percent Display element
or to a higher level display element containing it.
As with any display element, you may add an action sub-model named
<On Click> to model what should be done if the user selects
the displayed number, but this is seldom needed.
For best results, use the Firefox browser..