Not too long ago, I explained why why there is a weird wReserved value at the start of the DECIMAL structure. Markus Grohs pointed out in a comment that the way that decVal is overlaid on top of a VARIANT means that you have to be careful about the order in which you set the fields.GivenDECIMAL value = ⟦ some value ⟧;VARIANT var;VariantClear(&var);then you have to remember to set the vt last because it is overwritten by the wReserved inside the DECIMAL.// Wrongvar.vt = VT_DECIMAL;var.decVal = value; // oops, the wReserved overwrites the var.vt.// Bettervar.decVal = value; // the wReserved overwrites var.vtvar.vt = VT_DECIMAL; // but we fix it up immediatelyThe extra wReserved in the DECIMAL is like a bulky backpack that you wear as you go about your daily business. You usually forget that you have it on, until you turn around in a tight spot and accidentally knock something over.