Archival Resource Key, a means of creating persistent URLs uses a standard maintained by the California Digital Library https://confluence.ucop.edu/display/Curation/ARK It is implemented using the redirect settings of an apache webserver to point to directory structures and is intended to provide a persistent URL - by publishing a URL and associating it with a digital object an intention is stated to maintain that link into the future.
The use of apache redirects also means that it is possible to add to the end of the ARK additional text that performs different behaviours. To illustrate, the ARK for the IIIF manifest for a manuscript - Durham University Library is
which resolves to
(the pattern resolved in the apache redirect can be seen in the relation between t1mcz30ps64z and /t1/mc/z3/t1mcz30ps64z).
In addition a rewrite rule can be added so that by adding .html to the ARK the manifest is passed through into a IIIF viewer, so
will open the manifest in the University's local implementation of the Mirador viewer. A second value can be added after a forward slash which contains the short ark form for a canvas within the manifest, thus
which is a shortened form of
which is in turn a shortened form of the full url of the viewer, manifest and canvas
Durham University Library's NAAN (Name Assigning Authority Number) is registered as 32150
Durham University Library's name to thing server, which interpets and redirects ARKs, is https://n2t.durham.ac.uk