BBY/ABY is used to position items along the Star Wars Timeline. BBY refers to Before the Battle of Yavin. ABY refers to After the Battle of Yavin. The Battle of Yavin in Episode IV: A New Hope occured in 0 BBY/ABY.
The Youtini Expanded Universe Ranking system is a 1-5 scale that ranks EU book quality, difficulty, and importance. Books closer to Level 1 are easier to read and understand, more important, and of higher quality.
Tycho Celchu has infiltrated the Imperial Forces. Now he can communicate vital strategic information that will give the Rebellion an upper hand! But when he's pressed to lead a raid on his old Rogue Squadron teammates, he must choose between saving his comrades and serving the cause.