I observed that there is a term called weekstone mentioned in SAP Notes. It is mentioned also in the Notes related to the HANA.
Even command "<INSTALL DIR>/HAN/HDB00/HDB version" outputs the weekstone like: weekstone: 0000.00.0
I think it has something to do with testing of how SAP does the test of next SPS or in general next releases of its software.
Can someone throw more light in the term weekstone?