That's correct. All schools keep class rank stats, internally. When it comes time to put together your dean's letter, they will use language like "is a good candidate" for the bottom quartile, "great candidate" for the second to bottom quartile, "excellent candidate" for the second to top quartile, or such. Obviously this may not be exactly what your schools does, but you get the idea.
For the highest ranking students, obviously, they usually will include good language such as "top of the class" or "top 10". And then of course, there are the AOA people. The fact that your school even HAS AOA status is proof positive that they MUST be keeping a rank for each student in their system. And if you are gunner enough that you are concerned about AOA rank, just chill the eff out cuz you're only an M1. Don't forget that AOA is based on your second year score, and that your USMLE Step 1 score is a large portion (50% at my school) of your class rank in a lot of systems anyway.
They will NEVER say something like "this student was in the bottom 25% of his/her class".
How stupid would that be for your school. Your reputation = the school's reputation. If they don't help you secure a good residency, then they are hurting their own reputation as well.
Hope this helps or makes you feel better.