In some (rare) cases, more than one business may be migrated as part of the same project. That is to be kept separate but use the same Mapping logic. 

An example could be multiple separate organisations that need to be migrated at the same time to the same target system using the same Target Map. In this case, all the businesses are exported from the current systems together and migrated by hopp in one single project.

Each separate business being migrated in the same Project in this way is called a Partition.

(A side note: Even though two businesses can be said to be involved in a merger migration because one business is merged into the other, a merger only involves one partition).

Migrations involving more than one Partition are rare. 

Nevertheless, it is paramount that the entire migration setup can handle them when they do occur. For instance, the hopp migration solution separates the data and Events concerning each partition and has authorization mechanisms in place to control that business users from one Partition (Organisation A) cannot view data from another Partition (Organisation B).