The identifier has a hierarchical structure as follows:[1] where NSS is the Namespace Specific String composed as follows: where:
In that kind of public use, the need for a central authority las a unique and necessary URN-resolver[broken anchor] is a problem.
In that context, the identifier's user must query the authority about the correct ID from some object's metadata, like year or title.
A common use of Lex URNs is to express "transparent identifiers", which can be built up by simple rules or inferences from basic metadata.
For example, the Brazilian Lex URN is used for both legislative and case law unique and universal identifier, using rules of formatting and abbreviation of the authority's name, the publication date, and the local identifier in the title of the document.