The hidden property indicates that the element should not be displayed.
hidden property values:
By default, all elements are visible. You can use the hidden property to hide an element, such as a formField or a groupbox. The runtime system handles hidden formFields. If you write an INPUT statement using a hidden field, the field is ignored (as if it was declared as noEntry). Programs may change the visibility of formFields dynamically with the ui.form built-in class.
When set the hidden property to true, the underlying item property is set to 1. The value 1 indicates that the element is hidden to the user without the possibility of showing the element, for example with the context menu of table headers. In this hidden mode, the unHidable property is ignored by the front end.
When you set hidden to user, the underlying item property is set to 2. The value 2 indicates that the element is hidden by default, but the user can show/hide the element as needed. For example, the user can change a hidden column back to visible. Form elements like table columns that are hidden by the user might be automatically reshown (hidden=0) by the front-end if the program dialog gives the focus to that field for input. In such case the program dialog takes precedence over the hidden property.
When you set a hidden property for a formField, the model node gets the hidden property, not the view node.formFields hidden with the user option (value 2) might be shown anyway if the field is needed by a dialog for input.