The following is in the key of C minor.

In most cases the accidental associated with the start and end of each tree that makes up the scale is the natural sign, which is what we would expect. However, if you look at the start of the third tree in the composition on page 7 (6/5 → 4/3) you'll notice that the E does not have a flat sign as its accidental. This is because notes are placed on the staff according to the conventions of equal temperment. The justly intoned E-flat being played here has a frequency of 627.84, whereas in equal temperment it is 622.254. The difference in cents is about 15 cents which is enough for its accidental to be a microtonal one.