What is important are the guidelines (agreements) and not any registration numbers, or have you ever seen a registration number for a zinc coffin?

By the way, there are hardly any pure zinc coffins left in Europe, these would be much too heavy and would cost far more than 500,- Euro, the coffins we receive in Germany are only zinc sheet coffins, i.e. galvanized sheet metal and these are also not mentioned in any legal text and are also not rottable, as originally intended.

Important here is the Paragraph 6 i) & (ii) of the Strasbourg Agreement. In addition to a zinc coffin, another container can be chosen; it is important that it is 100% airtight and impermeable to liquids.

Here the original text from the Strasbourg Agreement:

European Convention on the Carriage of Corpses of 26.10.1973
(Strasbourg Agreement)

The member States of the Council of Europe signatory to this Convention, considering the need to simplify the formalities for the international transport of corpses, and bearing in mind that the transport of corpses does not constitute a health hazard even if the death was due to a communicable disease, provided that appropriate measures are taken, in particular with regard to the impermeability of the coffin, have agreed as follows:

…… Article 6
(1) The coffin must be impermeable and lined with absorbent materials. If the competent authority of the State of departure deems it necessary, the coffin must be fitted with a pressure equalisation device to balance the internal and external pressures. It must consist of

(i) either an outer wooden coffin with a minimum wall thickness of 20 mm and a carefully soldered inner coffin of zinc or any other self-decomposing material

(ii) or a single wooden coffin with a wall thickness of at least 30 mm, lined with a layer of zinc or other self-decomposing material

2. Where death is due to a contagious disease, the body shall be wrapped in a shroud soaked in an antiseptic solution.

3. Without prejudice to paragraphs 1 and 2, in the case of transport by air, the coffin shall be fitted with a pressure equalisation device or, failing that, shall have such guarantees of strength as are recognised as sufficient by the competent authority of the State of departure………