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.
When Hoole decides to visit the planet Gobindi, even a warning from Tash's anonymous Holonet contact isn't enough to change his mind. He's determined to study the planet's ancient ruins. For Tash, it's a chance to discover what her mysterious uncle is really up to.