Original: Salonen's tenure with the orchestra first began with a residency at the 1992 Salzburg Festival in concert performances and as the pit orchestra in a production of the opera Saint-François d'Assise by Olivier Messian; it was the first time an American orchestra was given that opportunity.
Simplified: At the beginning of Salonen's time with the orchestra they gave regular performances at the Salzburg Festival and they played for a production of the opera Saint-François d'Assise by Olivier Messiaen.