Hi,
The internal id can be seen by modifying your registry entry, which you can refer to this link:http://scn.sap.com/community/mdm/netweaver-mdm/blog/2012/03/21/enable-record-ids-tooltip-in-data-manager
You need to import the internal id when you check out, and the system will return a new internal id if the check out is successful. The original record is protected and can't be modified until you check in or roll back by using the new internal id. After you check in or roll back, the new internal id disappears and the original record can be modified again.
In other cases, when you want to create a new record, you can check out the record by setting the parameter checkOutAsNew (exclusive or non-exclusive). After checked in, the new record can be seen by other users.