Eur

Because it has been published; retirement from ISO 639 does not remove it completely. The code remains frozen indefinitely (and kept in that state for reference). In fact it is marked as "deprecated", see https://iso639-3.sil.org/code/eur (note that ISO 639 is not the only user of these codes and various codes have been "retired" in ISO 639 but kept in BCP47, some of them reappearing later; deprecation jsut means that any documents created tagged with that code remains valid, even if it is not suitable for new documents, and that some of them may be requalified later possibly with another existing code or a private-use code).