Attention!!! This is very important information. It will make understand certain time-lines and possible mistakes that sometimes may occur in people´s minds, due to misinformation and unrecommended reading. Do not follow the wrong path, young padawan. I´m here to guide you throughout the Force.
Atenção!!! Esta informação é muito importante. Farte-a compreender as linhas temporais e possíveis enganos que possam ocorrer nalgumas mentes, devido a má informação e leitura não recomendada. Não sigas o trilho errado, jovem padawan. Estou aqui para guiar-te através da Força.
The Great ReSynchronization occurred in 35 BBY as a method of the Republic Measures & Standards Bureau to recalibrate the disparate dating systems used by the Galactic Republic. It was since used as a zero year for the dating system; thus, the Battle of Geonosis takes place in the year 13, the Great Jedi Purge in the year 16, Battle of Yavin in the year 35, and the Battle of Endor in the year 39. The Seventh Battle of Ruusan occurred in the year 964BrS.
Dates using the ReSynchronization are written in the following format:
Dates after ReSynchronization do not include trailing characters. Dates occurring before the ReSynchronization are followed by "BrS", for Before ReSynchonization:
The dating system introduced with the Great ReSynchronization was still used during the Imperial period, although some Imperials preferred to use the establishment of the Galactic Empire (19 BBY) as the starting point. The Great ReSynchronization system eventually became obsolete under the New Republic and replaced in 25 ABY with the current Galactic Standard Calendar, centered around the Battle of Yavin (0 BBY).
Taken from the great Wookieepedia.
Mauro Bex : maurobindo