It's reasonable to display just HTML content in Pdf documents and sometimes you may also want display content in the same HTML format. Therefore the new coming property in Text Object Text.IsHtmlTagSupported is generated to match such requirements.
Its default value is false if you just want to show the content in HTML. So you should set it to true if you want to display HTML format.
Please go to Text.IsHtmlTagSupported for details. Also you can get information in the following page: