Hi jurn
It looks to me that the DRP units have been issued under a different code - in this case WDCN.
Reading through the Appendix 3B announcement on the 27/2 I see it says that the New Securities will rank for future distributions from March 1 but for the June 30 distribution these new DRP units will participate in the ratio 122/181.....ie....for the June 30 distribution these new DRP units will receive a distribution equal to 122/181 times whatever the WDC units' distribution will be.
Therefore since the distribution rates for these DRP units and the ordinary WDC units will be different on June 30 they have to be kept and traded separately on the market. I would imagine that after June 30, assuming the DRP shares will participate equally in subsequent distributions, the WDCN units will be incorporated into the WDC code.
In the mean time you will have a small separate parcel of WDCN until June 30
cheers
bullmarket