What was in the update I just got?

[WarnerYoung]

I finally managed to borrow an AT&T SIM card from a friend to update my AT&T Galaxy Note 4. I got it up to Android 5.1, then there was a new update that was only 62MB. Now it says the baseband level is N910AUCU2DOI3. So what was in such a small update? And are there a bunch more small updates like this before I can get my phone up to Marshmallow?

 

[Tim1954]

Likely the monthly security patch...

 

[WarnerYoung]

Tim1954, thanks! Yeah, I think you're right.