A high-level description of the design and ACIs for trusts is available at https://www.redhat.com/archives/freeipa-devel/2011-December/msg00224.html and https://www.redhat.com/archives/freeipa-devel/2011-December/msg00248.html Ticket #1731
The update files are sorted before being processed because there are cases where order matters (such as getting schema added first, creating parent entries, etc). 10 - 20: Schema 20 - 30: FDS Configuration, new indices 30 - 40: Structual elements of the DIT 40 - 50: Pre-loaded data