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.
Vader's story continues! Jocasta Nu, the Jedi Temple librarian, puts forth a desperate effort to gather and preserve whatever she can of the Jedi legacy after the purge. Vader and the Grand Inquisitor cannot let Jocasta succeed and are sent after her, as Palpatine views her as a particular threat. Her knowledge makes her almost a one-woman Jedi Order that must be stopped.