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.
No sooner has Darth Vader's funeral pyre burned to ashes on Endor than the Alliance intercepts a call for help from a far-flung Imperial outpost. Bakura is on the edge of known space and the first to meet the Ssi-ruuk, cold-blooded reptilian invaders who, once allied with the now dead Emperor, are approaching Imperial space with only one goal: total domination.
Princess Leia sees the mission as an opportunity to achieve a diplomatic victory for the Alliance. But it assumes even greater importance when a vision of Obi-Wan Kenobi appears to Luke Skywalker with the message that he must go to Bakura - or risk losing everything the Rebels have fought so desperately to achieve.