Bread-Bakers v101.n006.14

I have two questions as a new bread baker.  l.  What is "A-P" flour? and 2. 
What is meant by refreshing a sourdough starter?  I really do enjoy this 
bread-bakers list.  Everyone that posts is so helpful and so 
friendly.  Feels like a family out there.  Hoping you can answer these two 
question.....

Have a good day, Betty Hodge