This is the identifier used by Business Object Modules to determine the type of the Business Object. Therefore, it must be unique for each Business Object Type and it must be possible for a Business Object Module implementation to identify the type of the Business Object from the identifier. It is important to ensure that this type name does not collide with any other Business Object Types available in the system i.e., it should not collide with the names of the Business Object Types provided out-of-the-box, or with any other Business Object Types developed by customer organizations. To guarantee this, it is recommended that Business Object Type names developed externally to the application are prefixed with a short abbreviation or name identifying the organization.
So, for an organization called "Sample Organization", the Business Object Type Identifier for the Folder Business Object Type could be "so.Folder". Similarly, for the User Business Object Type; it could be "so.User".