Using this flow plan, can someone help me understand better by using this example? Maybe it will help others too.

1826 and 1830 are in the same (current) class for OCL as of the January bid.

In this April Bid, 1826 is displaced, but 1830 who is junior gets to keep the seat. Their names are side by side, and all equal for the January Bid.

What does the "Y" and "NN" mean? Is it proffer to displace and not enough bids? Does that explain how this happens? Maybe a stupid question but it is not obvious to me looking at the seniority.

1826 had the "Y" and "NN" next to their name while 1830 had nothing. 1826 shows up twice on the flow plan while 1830 shows up once. This is not an intuitive system to me yet.