SAP objects in Customer Namespace

Ever wondered why object starting with Y*/Z* is prompting for Access keys when we try to modify it. Or during upgrade, ever startled by Y*/Z* objects in SPDD/SPAU list.

Here's the reason:

SAP delivers a few system objects with names that fall within the customer name range. These objects already existed when the customer name range was extended from YY*/ZZ* to Y*/Z*. 

One can find all such objects in database table TDKZ.