Practical application of what rudderrudderrat posted (my understanding anyway):
If current pitch + pitch change in last second > 9.25 deg (depending on type), you'll get the alert.
So if you snatch flare for some reason, and reach a pitch of 7 deg in one second (4.5 deg change from 2.5 deg approach attitude): 7 + 4.5 = 11.5 and "pitch pitch"...