A J Lab file combines a text description and executable J code in a single file. The Lab system lets you step through the file, displaying the text and executing the code. The user is in a normal J session, and can try out other J expressions while running the lab.
A Lab is structured into one or more chapters, each containing one or more sections. The user can go through chapters in any order, but the sections within each chapter must be run sequentially.
Lab files are ordinary text files with extension .ijt. You can create the ijt files using any text editor.
The gui JFE provides menu item access to running labs, for example in the Qt IDE, select menu Help|Studio|Labs...