How long does temporary admission of inputs last under 29-89, and can it be extended?

Art. 12 suspends payment of customs duties and import taxes (VAT included) on raw materials, semi-finished and intermediate products, materials, containers, packaging and labels needed in order to export,… in line with the lists authorized in MINECO's qualification resolution,… for up to one (1) year from acceptance of the import customs declaration or of the FAUCA. The text in force, as amended by Decree 19-2016, contains no extension clause: the rule allowing an extension "once only and for up to an equal period", requested 30 days before expiry, appears solely in the original 1989 text (SICE/OAS) and did not survive the reform.