229 Neb. Admin. Code, ch. 14, § 004
Boilers and pressure vessels that are condemned by the Chief Boiler Inspector or a Deputy Inspector shall have, distinctly stamped over the State of Nebraska serial number, the following symbol: "XXX". In addition to stamping the metal tag the inspector shall affix a label to the unit showing that the unit has been condemned. If the metal tag is not on the unit, a label showing the serial number shall be attached to the unit. In the case of boilers that have numbers that are not physically stamped but are identified by an alternative labeling, the Chief Boiler Inspector or Deputy Inspector shall remove or destroy the alternative labeling device and then write "Condemned" in a conspicuous place on the unit.
229 Neb. Admin. Code, ch. 14, § 004