Avoiding creation of WO for Line Type W

Hi,

We have defined a generic item as line Type "W". This works fine for us when we create a SO (rather ST transfer order) for this item and it automatically creates a WO.  The issue is when there a blanket order for this item we do not want any WO created. Can we achieve this (i.e. SO not creating WO for an item with line type W).

(We are on A 7.3 cume 12)

Thanks,

NG