Provisional attachment of property protects customs revenue during pending duty proceedings, subject to approval and time limits. Provisional attachment of property may be ordered during pending customs duty proceedings where the proper officer considers it necessary to protect revenue, subject to prior approval and compliance with prescribed rules. The attachment applies to the noticee's property and must be made by written order. It ceases after six months, though the specified senior customs authority may extend the period for recorded reasons up to a maximum total extension of two years, excluding the period spent in settlement proceedings before the Settlement Commission.