Measures can contain less notes than the time signature says. Here, the first and third measures contain only two quarters instead of four. MusicXML Part 1 4 4 G 2 A 4 1 1 quarter A 4 1 1 quarter A 4 1 1 quarter A 4 1 1 quarter A 4 1 1 quarter A 4 1 1 quarter A 4 1 1 quarter A 4 1 1 quarter A 4 1 1 quarter A 4 1 1 quarter A 4 1 1 quarter A 4 1 1 quarter