def attachment_ids!(aids)
      @nbuild.AttachmentIds {
        @nbuild.parent.default_namespace = @default_ns
        aids.each do |aid|
          attachment_id!(aid)
        end
      }
    end
def attachment_ids!(aids)
      @nbuild.AttachmentIds {
        @nbuild.parent.default_namespace = @default_ns
        aids.each do |aid|
          attachment_id!(aid)
        end
      }
    end
Build the AttachmentIds element
 @see http://msdn.microsoft.com/en-us/library/aa580686.aspx