The essential difference between the ijt and rtf file is that the text part of each section in the rtf file can contain formatting such as bold, superscript and color. When the lab is run, the formatted text is displayed in a Windows form with a rich-text control.
If you close the form, the lab can be run in the session in the usual way.
The facilities available in the Windows rich-text control are those of WordPad, and are a subset of those in Word and other word processors. Formatting instructions not supported by the rich-text control are ignored.
The layout of the rtf file is exactly the same as for the ijt file. Formatting for the non-text sections is ignored, and it may be helpful to apply distinctive formatting to each section to make it easy to read.
LABWIDTH and LABWRAP are ignored by the rich-text control, except when the text window is closed and the lab run in a J session.