Annex A.3 of prEn 16157-1 as submitted to CCMC for publication describes rules how UML qualifiers are mapped to XSD. The tool implements these rules and the mapping is consistent with the handling of qualiifers in earlier DATEX II versions. Qualifiers are actually used throughout the Level A model, as is the basis for EN 16157-2, 3 and 7 and will be the basis for further parts of the standard.
Nevertheless, there is no rule mentioning the use of UML qualifiers in the main section of the document.
Add the following section to clause 7.2:
7.2.8 UML Associations may have a “qualifier“ UML Property.