Execution windows are distinguished by their file extension of .ijx. When you load J, it creates a new execution window for the session. These windows are named 1.ijx, 2.ijx etc. By default, 1.ijx is used, however, if a file of this name already exists, the next available unused name is picked.
You can type sentences into an execution window. When you press Enter, the system reads the line on which the cursor is positioned. If this line is at the foot of the execution window, it is executed and the result displayed below. Otherwise, the line is copied to the foot of the execution window - press Enter again to execute it.
The execution windows 1.ijx, 2.ijx and so on represent temporary files. That is, while the J session is active, if you have a window 2.ijx, then there is a file of that name (temp\2.ijx), but when you close the window or terminate the J session, this file is deleted. If you want to save these files, you must explicitly save them with a name other than n.ijx (for integer n); for example, mywork.ijx. If you do save an execution window in this way, the session manager treats it as a permanent file, and will save the file again when you close the window or terminate the session. You can load it in your next session - it will again be treated as a permanent file.
In no case are you prompted when closing an execution window - if it is temporary, the file is deleted; if it is permanent, the file is saved.
Note that closing an execution window, closes the J session.