The Document Registration widget shows the registration number of an app item. Please note that registration is only available for the Document type apps. More information about registration can be found in this article.
To configure the widget, drag it to the canvas or click +Widget. Enter the settings in the pop-up window.
When you edit the app form, the Item* and Displayed fields* are defined automatically.
The Hide, Read only, HTML styles, On mouse enter handler, On mouse leave handler settings are the system widget settings. Read more about them in this article.
To finish the configuration, click Save and Publish.