If you leave a field blank in an eConnect update, nothing will change on in the data. So, how would you blank the field?
This idea came from David Musgrave's blog
http://blogs.msdn.com/b/developingfordynamicsgp/archive/2011/08/26/quick-tip-using-econnect-to-update-customer-or-vendor-addresses-with-a-blank-address-line-3.aspx
I'm copying the substance of it here so that I won't lose it. David's article is much better than mine <smiles>