A digital object identifier (DOI) is a character string (a "digital identifier") used to uniquely identify an object such as an electronic document. Metadata about the object is stored in association with the DOI name and this metadata may include a location, such as a URL, where the object can be found. The DOI for a document is permanent, whereas its location and other metadata may change. Referring to an online document by its DOI provides more stable linking than simply referring to it by its URL, because if its URL changes, the publisher need only update the metadata for the DOI to link to the new URL.^[1][2][3]

Organizations that meet the contractual obligations of the DOI system and are willing to pay to become a member of the system can assign DOIs.^[4] The DOI system is implemented through a federation of registration agencies coordinated by the International DOI Foundation,^[5] which developed and controls the system. The DOI system has been developed and implemented in a range of publishing applications since 2000; by late April 2011 more than 50 million DOI names had been assigned by some 4,000 organizations.^[6] The DOI system is part of the larger Handle System.^[7]

DOI names[link]

A DOI name takes the form of a character string divided into two parts, a prefix and a suffix, separated by a forward slash. The prefix identifies the registrant of the name, and the suffix is chosen by the registrant and identifies the specific object associated with that DOI. Most legal Unicode characters are allowed in these strings, which are interpreted in a case-insensitive manner.

For example, in the DOI name 10.1000/182, the prefix is 10.1000 and the suffix is 182. The "10." part of the prefix identifies the DOI registry,^[8] and the characters 1000 in the prefix identify the registrant; in this case the registrant is the International DOI Foundation itself. 182 is the suffix, or item ID, identifying a single object (in this case, the latest version of the DOI Handbook). Citations using DOI names should be printed as doi:10.1000/182. When the citation is a hypertext link, it is recommended to embed the link as a URL by concatenating "http://dx.doi.org/" to the DOI name, omitting its "doi:" prefix; e.g., the DOI name doi:10.1000/182 is linked as http://dx.doi.org/10.1000/182. This URL provides the location of an HTTP proxy server which will redirect web accesses to the correct online location of the linked item.^[4][9]

DOI names can identify creative works (such as texts, images, audio or video items, and software) in both electronic and physical forms, performances, and abstract works^[10] such as licenses, parties to a transaction, etc. The names can refer to objects at varying levels of detail: thus DOI names can identify a journal, an individual issue of a journal, an individual article in the journal, or a single table in that article. The choice of level of detail is left to the assigner, but in the DOI system it must be declared as part of the metadata that is associated to a DOI name, using a data dictionary based on the indecs Content Model.

Applications[link]

Major applications of the DOI system currently include:

• persistent citations in scholarly materials (journal articles, books, etc.) through CrossRef, a consortium of around 3,000 publishers;
• research datasets through DataCite, a consortium of leading research libraries, technical information providers, and scientific data centers;
• European Union official publications through the EU publications office.

In the Organisation for Economic Co-operation and Development's publication service SourceOECD, each table or graph in an OECD publication is shown with a DOI name that leads to an Excel file of data underlying the tables and graphs. Further development of such services is planned.^[11]

A multilingual European DOI registration agency activity, mEDRA, and a Chinese registration agency, Wanfang Data, are active in non-English language markets. Expansion to other sectors is planned by the International DOI Foundation.^{[citation needed]}

Features and benefits[link]

The DOI system was designed to provide a form of persistent identification, in which each DOI name unequivocally and permanently identifies the object to which it is associated. And, it associates metadata with objects, allowing it to provide users with relevant pieces of information about the objects and their relationships. Included as part of this metadata are network actions that allow DOI names to be resolved to web locations where the objects they describe can be found. To achieve its goals, the DOI system combines the Handle System and the indecs Content Model with a social infrastructure.

The Handle System ensures that the DOI name for an object is not based on any changeable attributes of the object such as its physical location or ownership, that the attributes of the object are encoded in its metadata rather than in its DOI name, and that no two objects are assigned the same DOI name. Because DOI names are short character strings, they are human-readable, may be copied and pasted as text, and fit into the URI specification. The DOI name resolution mechanism acts behind the scenes, so that users communicate with it in the same way as with any other web service; it is built on open architectures, incorporates trust mechanisms, and is engineered to operate reliably and flexibly so that it can be adapted to changing demands and new applications of the DOI system. DOI name resolution may be used with OpenURL to select the most appropriate among multiple locations for a given object, according to the location of the user making the request.^[12] However, despite this ability, the DOI system has drawn criticism from librarians for directing users to non-free copies of documents that would have been available for no additional fee from alternative locations.^[13]

The indecs Content Model is used within the DOI system to associate metadata with objects. A small kernel of common metadata is shared by all DOI names and can be optionally extended with other relevant data, which may be public or restricted. Registrants may update the metadata for their DOI names at any time, such as when publication information changes or when an object moves to a different URL.

The International DOI Foundation (IDF) oversees the integration of these technologies and operation of the system through a technical and social infrastructure. The social infrastructure of a federation of independent registration agencies offering DOI services was modelled on existing successful federated deployments of identifiers such as GS1 and ISBN.

Comparison with other identifier schemes[link]

A DOI name differs from commonly used Internet pointers to material, such as the Uniform Resource Locator (URL), in that it identifies an object as a first-class entity,^{[clarification needed]} not simply the place where the object is located. It implements the Uniform Resource Identifier (Uniform Resource Name) concept and adds to it a data model and social infrastructure.^[14]

A DOI name also differs from standard identifier registries such as the ISBN, ISRC, etc. The purpose of an identifier registry is to manage a given collection of identifiers, whereas the primary purpose of the DOI system is to make a collection of identifiers actionable and interoperable, where that collection can include identifiers from many other controlled collections.^[15]

The DOI system offers persistent, semantically interoperable resolution to related current data, and is best suited to material that will be used in services outside the direct control of the issuing assigner (e.g., public citation, or managing content of value). It uses a managed registry (providing social and technical infrastructure). It does not assume any specific business model for the provision of identifiers or services, and enables other existing services to link to it in defined ways. Several approaches for making identifiers persistent have been proposed. The comparison of persistent identifier approaches is difficult because they are not all doing the same thing. Imprecisely referring to a set of schemes as "identifiers" doesn't mean that they can be compared easily. Other "identifier systems" may be enabling technologies with low barriers to entry, providing an easy to use labeling mechanism that allows anyone to set up a new instance (examples include Persistent Uniform Resource Locator (PURL), URLs, Globally Unique Identifiers (GUIDs), etc.), but may lack some of the functionality of a registry-controlled scheme and will usually lack accompanying metadata in a controlled scheme. The DOI system does not have this approach and should not be compared directly to such identifier schemes. Various applications using such enabling technologies with added features have been devised that meet some of the features offered by the DOI system for specific sectors (e.g., ARK).

A DOI name does not depend on the object's location and, in this way, is similar to a Uniform Resource Name (URN) or PURL but differs from an ordinary URL. URLs are often used as substitute identifiers for documents on the Internet (better characterised as Uniform Resource Identifiers) although the same document at two different locations has two URLs. By contrast, persistent identifiers such as DOI names identify objects as first class entities: two instances of the same object would have the same DOI name.

Resolution[link]

DOI name resolution is provided through the Handle System, developed by Corporation for National Research Initiatives, and is freely available to any user encountering a DOI name. Resolution redirects the user from a DOI name to one or more pieces of typed data: URLs representing instances of the object, services such as e-mail, or one or more items of metadata. To the Handle System, a DOI name is a handle, and so has a set of values assigned to it and may be thought of as a record that consists of a group of fields. Each handle value must have a data type specified in its "<type>" field, that defines the syntax and semantics of its data.

To resolve a DOI name, it may be input to a DOI resolver (e.g., at www.doi.org) or may be represented as an HTTP string by preceding the DOI name by the string

http://dx.doi.org/

For example, the DOI name 10.1000/182 can be resolved at the address "http://dx.doi.org/10.1000/182". Web pages or other hypertext documents can include hypertext links in this form. Some browsers allow the direct resolution of a DOI (or other handles) with an add-on, e.g., CNRI Handle Extension for Firefox. The CNRI Handle Extension for Firefox enables the browser to access handle or DOI URIs like hdl:4263537/4000 or doi:10.1000/1 using the native Handle System protocol. It will even replace references to web-to-handle proxy servers with native resolution.

Organizational structure[link]

The International DOI Foundation (IDF), a non-profit organisation created in 1998, is the governance body of the DOI system.^[16] It safeguards all intellectual property rights relating to the DOI system, manages common operational features, and supports the development and promotion of the DOI system. The IDF ensures that any improvements made to the DOI system (including creation, maintenance, registration, resolution and policymaking of DOI names) are available to any DOI registrant. It also prevents third parties from imposing additional licensing requirements beyond those of the IDF on users of the DOI system.

The IDF is controlled by a Board elected by the members of the Foundation, with an appointed Managing Agent who is responsible for co-ordinating and planning its activities. Membership is open to all organizations with an interest in electronic publishing and related enabling technologies. The IDF holds annual open meetings on the topics of DOI and related issues: the 2010 meeting is provisionally scheduled to be held in Hannover, Germany in mid year.

Registration agencies, appointed by the IDF, provide services to DOI registrants: they allocate DOI prefixes, register DOI names, and provide the necessary infrastructure to allow registrants to declare and maintain metadata and state data. Registration agencies are also expected to actively promote the widespread adoption of the DOI system, to cooperate with the IDF in the development of the DOI system as a whole, and to provide services on behalf of their specific user community. A list of current RAs is maintained by the International DOI Foundation.

Registration agencies generally charge a fee to assign a new DOI name; parts of these fees are used to support the IDF. The DOI system overall, through the IDF, operates on a not-for-profit cost recovery basis.

Standardization[link]

The DOI system is an international standard developed by the International Organization for Standardization in its technical committee on identification and description, TC46/SC9.^[17] The Draft International Standard ISO/DIS 26324, Information and documentation - Digital Object Identifier System met the ISO requirements for approval. The relevant ISO Working Group later submitted an edited version to ISO for distribution as an FDIS (Final Draft International Standard) ballot,^[18] which was approved by 100% of those voting in a ballot closing on November 15, 2010.^[19] The final standard was published on April 23, 2012.^[20]

DOI is a registered URI under the infoURI^[21] specification (IETF RFC4452), "The "info" URI Scheme for Information Assets with Identifiers in Public Namespaces";^[22] info:doi/ is the infoURI Namespace of Digital Object Identifiers.

The DOI syntax is a NISO standard, first standardised in 2000, ANSI/NISO Z39.84-2005 Syntax for the Digital Object Identifier.^[23]

See also[link]

• Digital identity
• Object identifier
• Universally Unique Identifier (UUID)
• Metadata standards
• Publisher Item Identifier (PII)
• Permalink
• Persistent Uniform Resource Locator

Notes and references[link]

External links[link]

• Official website
• Factsheet: DOI System and Internet Identifier Specifications
• The Handle System
• DOI-Registration agency for data
• List of active DOI prefixes

In computing, an object identifier or OID is an identifier used to name an object (compare URN). Structurally, an OID consists of a node in a hierarchically-assigned namespace, formally defined using the ITU-T's ASN.1 standard.^{[citation needed]} Successive numbers of the nodes, starting at the root of the tree, identify each node in the tree. Designers set up new nodes by registering them under the node's registration authority. The root of the tree contains the following three arcs:

• 0: ITU-T
• 1: ISO
• 2: joint-iso-itu-t

Usage[link]

• In computer security, OIDs serve to name almost every object type in X.509 certificates, such as components of Distinguished Names, CPSs, etc.
• Within X.500 directory schemas and protocols, to uniquely name each attribute type and object class, and other elements of schema.
• Within LDAP schemas, each object class and each attribute type has a unique OID
• In computer networking, an OID, in the context of the Simple Network Management Protocol (SNMP), consists of the object identifier for an object in a Management Information Base (MIB).
• HL7, DICOM and other health care related information interchange standards use OIDs for globally unique identifiers for both individual information objects as well as References to code systems and data element dictionaries. DICOM uses the term UID (Unique IDentifier) in place of OID.
• The IANA OID registry contains a list of registered entities that use OIDs to reference internal structures (e.g. directory attributes). Each entity is assigned an initial referential value (e.g. 1.3.6.1.4.1.5518 for TDS Telecom Inc.) and thereafter the internal numbering plan is up to the entity to define (e.g. 1.3.6.1.4.1.5518.1.5.47 might refer to the "CCID" attribute of the LDAP directory associated with customers). This allows for precise referencing of data attributes in a company or other entity.

Examples[link]

The most common OIDs seen "in the wild" usually belong to the private enterprise numbers allocated by IANA under the 1.3.6.1.4.1 (iso.org.dod.internet.private.enterprise) arc.

Another increasingly used form^[when?] of OID is in the area of health care and public health informatics in the United States. Health Level Seven (HL7), a standards-developing organization in the area of electronic health care data exchange, is an assigning authority at the 2.16.840.1.113883 (joint-iso-itu-t.country.us.organization.hl7) node. HL7 maintains its own OID registry, and as of January 1, 2008 it contained almost 3,000 nodes, most of them under the HL7 root. The Centers for Disease Control and Prevention has also adopted OIDs to manage the many complex values sets or "vocabularies" used in public health. The various OIDs are available in the Public Health Information Network (PHIN) Vocabulary Access and Distribution System (VADS).

See also[link]

• Digital object identifier
• LSID
• International Geo Sample Number
• Surrogate key
• Extended Validation Certificate
• Universally Unique Identifier
• Globally Unique Identifier
• Uniform Resource Name
• Persistent Object Identifier
• In computer programming, an object identifier generally takes the form of an implementation-specific integer or pointer that uniquely identifies an object. However, OIDs are a specific approach to creating globally unique object identifiers in a distributed system.
• OBJREFs have an object identifier (OID) field.

References[link]

This article is based on material taken from the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the "relicensing" terms of the GFDL, version 1.3 or later.

External links[link]

• Object Identifier Repository
• Harald Tveit Alvestrand's Object Identifier Registry
• IANA Private Enterprise Numbers

Chris Phillips
Born	(1978-03-09) March 9, 1978 (age 34) Calgary, AB, CAN
Height	6 ft 3 in (1.91 m)
Weight	215 lb (98 kg; 15 st 5 lb)
Position	Defence
Shoots	Left
NHL team	Ottawa Senators
National team	Canada
NHL Draft	1st overall, 1996 Ottawa Senators
Playing career	1997–present

Chris Phillips (born March 9, 1978) is a Canadian professional ice hockey player currently playing for the Ottawa Senators of the National Hockey League (NHL). He has been a member of the Ottawa Senators for his entire career, which began with the 1997–98 season. He also serves as their alternate captain and is regarded as a stay-at-home defenceman. The Senators drafted him first overall in the 1996 NHL Entry Draft. He was raised in Fort McMurray, Alberta.

Playing career[link]

Fort McMurray Oil Barons[link]

Phillips began his junior career with the Fort McMurray Oil Barons of the Alberta Junior Hockey League in 1993-94, where he had six goals and 22 points in 56 games. In 10 playoff games, Phillips had three assists. He returned to the Oil Barons for the 1994-95 season, in which he saw his offensive production increase to 16 goals and 48 points in 48 games. In 11 post-season games, Phillips had four goals and six points. Phillips also participated in the 1995 Canada Winter Games where he was the captain of the Alberta team.

Prince Albert Raiders[link]

Phillips joined the Prince Albert Raiders of the WHL for the 1995-96 season, where he had 10 goals and 40 points in 61 games as a rookie with the Raiders. Phillips helped the Raiders to the Conference Finals, as he had two goals and 14 points in 18 games. After the season, Phillips won the Jim Piggott Memorial Trophy and he was drafted first overall in the 1996 NHL Entry Draft by the Ottawa Senators.

The Senators assigned Phillips back to the Raiders for the 1996-97, and in 32 games, he had three goals and 26 points. The rebuilding team traded Phillips to the Lethbridge Hurricanes midway through the season.

Lethbridge Hurricanes[link]

Phillips finished the 1996-97 season with the Lethbridge Hurricanes, where he had four goals and 22 points in 26 games, helping the club finish in first place in the Central Division.

In the playoffs, Phillips finished second in team scoring with 25 points, as he had four goals and 21 assists, to help Lethbridge win the President's Cup, and earn a berth at the 1997 Memorial Cup held in Hull, Quebec.

In the Memorial Cup, Phillips had two goals and five points in five games, as the Hurricanes finished in second place in the tournament, as they lost to the Hull Olympiques in the final game.

Phillips was selected to the Memorial Cup all-star team, and won the 1996-97 Bill Hunter Memorial Trophy, which is awarded to the top defenseman in the WHL.

Ottawa Senators[link]

Phillips made his NHL debut in the 1997-98 season, when he appeared in 72 games with the Ottawa Senators, scoring five goals and 16 points, helping the club finish above .500 for the first time in team history. In 11 playoff games, Phillips had two assists, as Ottawa upset the New Jersey Devils in the first round, before falling to the Washington Capitals in the second round of the 1998 Stanley Cup Playoffs.

Phillips missed 48 games in the 1998-99, as he scored three goals and six points in 34 games with the Senators, before going pointless in three playoff games.

He saw his point total increase during the 1999-2000 season, as Phillips had five goals and 19 points in 65 games. In six playoff games, Phillips had an assist.

Phillips had another solid season with the club in 2000-01, appearing in 73 games, scoring two goals and 14 points, however, he suffered a late-season injury, in which he appeared in only one playoff game with the Senators. In that game, he scored his first ever playoff goal against Curtis Joseph of the Toronto Maple Leafs.

He remained a big part of the Senators blueline in 2001-02, as Phillips scored six goals and 22 points in 63 games. In 12 playoff games, Phillips did not register a point.

In 2002-03, Phillips helped the Senators win the Presidents' Trophy, which is awarded to the team with the best regular season record in the NHL. In 78 games, Phillips had three goals and 19 points. In the post-season, Phillips had a memorable goal for the Senators, as in game six of the Eastern Conference finals against the New Jersey Devils, Phillips scored the overtime winner, as Ottawa fought off elimination. The Senators lost the seventh game, but Phillips had a very successful playoff run, scoring two goals and six points in 18 games.

Phillips appeared in all 82 games for the first time of his career in 2003-04, as he scored seven goals and 23 points for the Senators. In the playoffs, Phillips once again had some overtime magic, as he scored the winning goal in the fourth game of the Senators first round series against the Toronto Maple Leafs. Toronto ended up winning the series in seven games, and that goal was Phillips only point of the series.

During the 2004-05 NHL lockout, Phillips signed with Brynäs IF of the SEL, where he had five goals and eight points in 27 games. In nine playoff games, Phillips had a goal and three points.

In 2005-06, he returned to the Senators, where Phillips had a goal and 19 points in 68 games. In nine playoff games, Phillips had two goals.

Phillips had his best offensive season of his career in 2006-07, as he had eight goals and 26 points as he played in all 82 games. Phillips had a +36 rating, which ranked him among the top of the NHL leaderboard. Prior to the season, the Senators named Phillips as an alternate captain, and on December 26, 2006, Phillips played in his 500th career game. In the playoffs, Phillips played over 23 minutes a game, shutting down the top offensive players of the Senators opponents, as he helped the team reach the 2007 Stanley Cup Finals, where the Senators lost in five games to the Anaheim Ducks. In 20 playoff games, Phillips had no points.

In 2007-08, Phillips had five goals and 18 points in 81 games, however, the Senators playoff run was short, as they were swept in the first round against the Pittsburgh Penguins, as Phillips was held pointless in four games.

The 2008-09 season saw the Senators struggle, as the team failed to make the playoffs for the first time since 1996. Phillips had another solid season, scoring six goals and 22 points in 82 games, however, he had a -14 rating, making it the first time since the 1998-99 season that Phillips was a minus player.

In 2009-10, the Senators returned to the playoffs, and Phillips played a key role, as he tied his career high of eight goals and had 24 points, the second highest point total of his career, and he played in all 82 games for the second season in a row. In six playoff games, Phillips had no points.

Phillips with the Senators, January 2011

Phillips had a poor 2010-11 season, as he scored only a goal and nine points, his lowest point total since 1998-99, and had a -35 rating, as Ottawa struggled and failed to qualify for the playoffs for the second time in three seasons.

International career[link]

Phillips played for Team Canada at the 1996 World Junior Ice Hockey Championships held in Boston, Massachusetts, where he was held pointless in six games, as Canada won the gold medal. He returned to the tournament in 1997, held in Geneva, Switzerland, where Phillips had an assist in seven games, helping Canada win the gold medal once again. He was named to the 1997 tournament all-star team.

Phillips played for the Canadians at the 2000 IIHF World Championship held in St. Petersburg, Russia, where he had no points in nine games, as Canada finished in fourth place. He returned for the Canadian team at the 2005 IIHF World Championship held in Vienna and Innsbruck, Austria, where the Canadians finished with a silver medal. In nine games, Phillips had an assist. Phillips represented Canada again at the 2009 IIHF World Championship held in Bern and Kloten, Switzerland, recording three assists in nine games as Canada won the silver medal.

Personal life[link]

Phillips and his wife Erin have three children: a son named Ben and two daughters, Niomi and Zowie. He is the nephew of the Edmonton Oilers radio broadcaster Rod Phillips.^[1]

Awards[link]

Canadian Hockey League

• Top Draft Prospect - 1996

Western Hockey League

• Jim Piggott Memorial Trophy (Rookie of the Year) - 1996
• Bill Hunter Memorial Trophy (Top Defenceman) - 1997

Career statistics[link]

International play[link]

Medal record
Competitor for  Canada
Ice hockey
World Championships
Silver	2009 Switzerland
Silver	2005 Austria
World Junior Championships
Gold	1997 Switzerland
Gold	1996 USA

• Gold medal at 1996 Under-20 World Championships
• Gold medal at 1997 Under-20 World Championships
• Silver medal at 2005 World Championships
• Silver medal at 2009 World Championships

References[link]

External links[link]

• Chris Phillips's NHL player profile
• Chris Phillips's career stats at The Internet Hockey Database