Its key signature has five flats….D-flat major. If the key has two flats, it uses the first two flats from the order of flats - Bb and Eb. If a key has one flat, it only contains the first flat from the order of flats - Bb. This order tells you which notes are flat in a key containing flats. The order of flats is a sequence of seven flat note names. What is the 1st flat in the order of flats in a key signature? This is the key of D flat because D flat is the second to last flat in the key signature. This is the key of E flat because E flat is the second to last flat in the key signature. For key signatures with flats, the key signature is the second to last flat. What is the key signature rule for flats?įlats. 11 How to write a natural minor key signature?.