code: public void assign(final Object a) {
  		setDerived(false);
  		setValue(a);
  		setDerived((a == null) ? false : true);
  		m_notKnown = false;
  	}
docs: /* (non-Javadoc)
  @see nz.co.senanque.validationengine.ProxyField#assign(java.lang.Object)