^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
 12            3  4          5       6  7        8 9

If the schema is urn, it is broken into its schema, NSI (Namespace Identifier) and NSS (Namespace Specific String).

Arguments:

Components

- is a one of uri_components(Scheme, Authority, Path, Search, Fragment) If a URI is parsed, i.e., using mode (+,-), components that are not found are left uninstantiated (variable). See uri_data/3 for accessing this structure. urn_components(Scheme, NID, NSS, Search, Fragment) Here Scheme is always urn. Otherwise the same comments as for uri_components/5 apply.