TrEd allows having multiple files open. In case the user tries to open a file while another file is already open, modified, and yet not saved (and the Don't close on open option is not checked) TrEd offers the user to save changes in the current file and close it, close it withought saving or to keep the file open. In the latter case, the file is not closed nor any changes are discarded but the file stays open and remains in the Session menu under the Open files label. Any number of files can be simultaneously open in this way. User may resume any open file and display it in the current window by choosing the corresponding item in the Session menu.