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.
The deadly assassin contracted by the Empire, X-7, is closer than ever to discovering the identity of his target. He's already infiltrated the top levels of the Rebel Alliance and gained Leia's trust. But he still hasn't been able to get Leia to give up the classified information he needs.
After all, Leia Organa is unbreakable: the youngest, toughest member of the Galactic Senate, and after its dissolution, the fiercest opponent of the Empire. She's survived kidnapping and torture under Darth Vader, but she's never had to do anything more difficult than her latest mission. She is going home.
And X-7 knows it will be the perfect opportunity to destroy her.