Migration from one application to another is extremely time consuming because you are: mapping from one set of entity types to another. Entities are the types of objects the application can hold (users/groups/documents/records/files/libraries/sites/retention rules etc) mapping from one set of descriptive metadata fields to another mapping from one set of functions to another. Functions are the actions that users can be permitted to perform on entities in the system (for example: create an entity/amend it/rename it/move it/copy it/delete it/attach a retention rule to it/grant or deny access permissions on it) mapping from one set of roles to another. Roles are simply collections of functions, grouped together to make it easier to administrate them. For example in SharePoint the role of ‘member’ of a site collects together the functions a user needs to be able to access a site and view and download content, and to contribute new content to the site, but denies them the functions they would need to administer or change the site itself.