I was told by an IO over the phone (when I called the NCSC and was transferred to the 2nd level) that the YL means you are in the queue to be scheduled for an interview. Supposedly one typically receives the IL within 3-6 weeks of receiving the YL. So, while it's not a guarantee that you will get the IL soon, it does indicate that you're moving through the process. Does anyone have any different information about the YL? I am simply relying on what the IO told me...