Oasis of The Mind Info Chart
The first column as labeled are the name of the main characters. The numbers in parentheses are their current age and the ID number below it is their current ID number.
The second column is their very first expiration date, the one that's been given since their birth by the government. The age indicates the age when they "expire", where they are given a choice whether to die or live another day by continuing to be the government's experiments. The ID number is the ID that they were given since birth. So you can see that both Changmin and Jaejoong have yet to "expire", meaning that they are still new to the system.
The third column is the second expiration date and it's basically the same as the first expiration date, only this time it's because during their first "expire" date, they had chosen to live another day. Therefore, they are given a new expiration date which is not known to them and their new ID number. So Yunho and Junsu are on their second expiration date.
The fourth column is basically the same as the columns before. Only Yoochun and Jihyo have survived being experiments to the government and are on their third expiration date. By now they know exactly how their government sort of works, although they are still in the dark about their future expiration dates.