The Rich Text Editor is displayed only for properties that have been configured with a special extension property value (see the topic Predefined Extension Properties for more information) and it allows the editor to create formatted HTML text in a WYSIWYG editor which is saved to the topic map as an HTML string.
An empty editor field displays as shown below:
Empty Rich Text Editor field
To start editing, click on the 
icon. The text editing environment will then load (this may take a few seconds) and display as shown below:
Rich Text Editor
With the editor you can enter text, format it with fonts, colors and other text effects; add tables and images and so on. The drag-handle in the bottom right-hand corner of the editor allows you to resize it if you need a larger editor window.
When you are finished editing, click on the 
icon to save your edits and the editor will close and the HTML will be rendered directly in the page.