Unusual High ID numbers in Mouse CCF

I’ve been noticing that some sections of the Adult Mouse Brain Atlas have unusually high ID numbers. Most ID numbers are somewhere between 1 and 10^5 while some are over 10^8 (for example Su3 with ID number 614454277). Is there reason for integer values this high compared to the rest of the CCF?

Those ids are generated by our database. Structures with much higher numbers were added to the database later. The CCF has been through several versions already as described in the documentation. These are the types of changes that make

But why is there a sudden jump in magnitude for these new IDs? Why is there a sudden change from ranges 1-10^5 to 10^8-10^9?

The ones with a very low number were imported from an earlier database.