Editing a Derived Column Transformation Expressions in SSIS 2008 r2 SSIS package

Hi,
I have the following Derived Column Expression in a  Data Flow Transformation in an SSIS package

[MSTUB-xInt_Only-Rev-Dt] == "00000000" ? NULL(DT_WSTR,10) : SUBSTRING([MSTUB-xInt_Only-Rev-Dt],5,4) + "-" + SUBSTRING([MSTUB-xInt_Only-Rev-Dt],3,2) + "-" + SUBSTRING([MSTUB-xInt_Only-Rev-Dt],1,2)

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This (I THINK)  replaces  values == "00000000" with NULLs
I now want to filter out “0 0 0 0” values also.
How do I amend the expression to accommodate this? Is it possible to add some kind of “OR”  to it?
Any guidance appreciated, thanks