I'm quite new to trying to read music. found a score for a fleetwood mac tune. in the 6th bar they use a flat symbol next to the 1st B is that just 1 accidental or are the next 6 B notes in that bar all Bb? heres a link to show you what i mean http://users.pandora.be/aurich/go_your_own_way.pdf
The Bb stays that way until the beginning of the next bar unless a natural sign pops up, which it doesn't in that song.
The tune is in F major which has one flat, the person that notated this didn't put the key signature in the staff but chose to notate by using accidentals to denote the Bb's.