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The concrete differences that we experience, such as restrictions on identifier as metadata (object descriptions) and , landing pages, and tool integration (eg, publishing tools), are not properties of identifier schemes per se, but properties of resolution, management, and management services extended citation services that various providers extend to or withheld from identifiers. Basic withhold from different identifier types. Those services are shaped in turn by communities of practice and by markets. Basic services are founded on a reliable database storing each identifier along with metadata elements (creator, title, date, redirection URL, etc) that describe the identified object. Extra services include link checking, duplicate detection, report generation, and searching.
Typically, scheme-based services are designed as siloes as silos ("walled gardens") to serve a particular identifier type (eg, Handle, DOI, or PURL). They all do Each silo does the same basic things – metadata, forwarding, etc – so the only point of building siloes is to capture markets and exclude others. Such a design requires artificially restricting database keys mapping names (identifiers strings) to things (objects or metadata). Excluding all but one type of identifier string may help to capture markets, but it's wasteful and non-inclusive. It requires building the same set of services over and over for each type and violates basic principles of openness, so the N2T (Name-to-Thing) resolver and EZID (identifiers made easy) management interface were designed to work with all identifiers. Work put into any new feature can be efficiently leveraged across all types, which sometimes creates surprising flexibility; for example, ARKs are often stored in EZID with "DOI metadata", and every DOI stored in N2T can benefit from "ARK resolution features" such as inflections and suffix passthrough, which are not available via the main DOI resolver (doi.org).
There are also softer differences, such as community attitudes and trends, based on numbers and "buzz". If we did free association in 2019, one might hear:
ARKs – libraries, archives, museums
DOIs – published literature (Crossref), published data (DataCite)
Handles – xxx
PURLs – linked data and semantic web
URNs – UUIDs, European libraries
It is hard to generalize how people use these identifiers. DOIs, for example, Generalizations about identifier types sometimes apply when resolution and management for that type is locked into one particular vendor or provider. For example, many PURL and Handle features and restrictions are well-defined by their respective administration silos. DOIs, which are built on top of Handles, have the same resolution features and restrictions as Handles, but metadata practices are diverse and evolving across registration agencies. DOIs used to be known primarily as identifiers for scientific and scholarly publications, with a mature community and service offering around "Crossref DOIs", but newer kinds of DOIs, such as those from DataCite and EIDR, are changing the nature of the DOI.
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Don't identifier types differ in metadata flexibility, content negotiation, inflections, and suffix passthrough?
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Content negotiation is a way for software to request descriptions of things that are not already in formats that might represent descriptions. Fortunately, to request descriptions without restriction, both humans and software can use inflections, exemplified by the '?' in the first answer. Backed by the right metadata, N2T is one of the few that does both.
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Why doesn't the global ARK resolver (n2t.net) have the word "ARK" in it?
N2T .net (Name-to-Thing) is a resolver originally built for ARKs. N2T stands for Name-to-Thing because strong values Principles of openness prevented it N2T from becoming just another DOI/Handle/PURL-type silo. As a result, , which all perform the same basic functions. Thus the "global ARK resolver" also resolves DOIs, Handles, PURLs, and URNs, along with and 600 other kinds types of identifier.
This counter-silo principle is can also be found in micro-service tools such as noid, which was built for ARKs but and is routinely widely used by organizations that mint ARKs and those that mint Handles.
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