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Frequently Asked Questions

  
OID standards
 
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Questions:
  1. What are the standards that define OIDs and the OID tree?
  2. Which kind of objects can be referenced by OIDs?
  3. Where can I learn more about OIDs and registration?
  4. How to add information to the OID repository?
  5. How to modify the description of an OID?
  6. How to delete an OID (or move it elsewhere in the OID tree)?
  7. How does the OID repository provided on this website compare with Harald Alvestrand's repository?
  8. How to reference an OID description in this repository?
  9. How many OIDs are currently described in this repository?
  10. How to get an OID assigned?
  11. What decision needs be taken if a country wants a national Registration Authority for OIDs?
  12. Are there guidelines or standards regarding subsequent arcs of a country arc?
  13. What is the Internet OID?
  14. Where does the dot notation for OIDs come from?
  15. Why are top-level arcs restricted to three arcs numbered 0 to 2, and why are arcs beneath root arcs 0 and 1 restricted to fourty arcs numbered 0 to 39?
  16. What do we call a registration tree (or object identifier tree)?
  17. What is the syntax of an OID?
  18. How is the entire registration tree managed?
  19. Which features are offered by this repository?
  20. What are the syntax rules to enter information about OIDs through the web interface?
  21. Which information is necessary to apply for an OID?
  22. Which information is necessary to register a UUID as an OID?
  23. What is the difference between the first and current Registration Authorities that appear in the description of some OIDs? What is their duty?
  24. What constraints are imposed to OIDs used in SNMP MIBs (Management Information Bases)?
  25. Is there a way to look up an OID in the OID repository from my web browser or email tool?
  26. What is a leaf OID?
  27. What is an orphan OID?

Answers:

  1. What are the standards that define OIDs and the OID tree?
    They are defined in the ITU-T Rec. X.660 | ISO/IEC 9834 series. A new release of this series has been published in 2004 by the ASN.1 group. These standards can be downlaoded for free from the ITU website or from the ITU-T SG17 dedicated web page.

  2. Which kind of objects can be referenced by OIDs?
    Objects that can typically be identified by an object identifier are (non exhaustively):
    • an ITU-T Recommendation, an ISO International Standard;
    • a country, a company, a project;
    • a certificate policy;
    • an encryption algorithm;
    • identification schemes (see ITU-T Rec. X.RA-nid under development)
    • an attribute of an X.500- or LDAP-based directory to make up a DistinguishedName;
    • an ASN.1 module, an ASN.1 type (or abstract syntax);
    • a set of ASN.1 encoding rules;
    • a MIB for SNMP network management;
    • a managed object class, one of its attributes, a notification or even other templates used in the area of network management and the GDMO standard (see ITU-T Rec. X.722 | ISO/IEC 10165-4);
    • an information object (see ITU-T Rec. X.681 | ISO/IEC 8824-2);
    • a ROSE operation (see ITU-T Rec. X.729 | ISO/IEC 9072-2);
    • the type of some part of an X.400 electronic message body;
    • a file format;
    • etc.

  3. Where can I learn more about OIDs and registration?
    A part from the official standards (see question 1), OIDs are presented in:
  4. How to add information to the OID repository?
     There are at least 4 ways of adding a new OID description to the repository:
    -1- Enter the OID value in the box under "Add a description for the following OID to the database" on the main page and click on the "Create" button; a new page will then be displayed with some boxes to fill. You can also enetr the OID in the following box:
         { }
    -2- Go to the father OID of the OID that you want to add and click on the "Create a child node" link on the top right-hand side of the page; a new page will then be displayed with some boxes to fill.
    -3- Go to an OID at the same level as the OID that you want to add and click on the "Create a brother node" link on the top right-hand side of the page; a new page will then be displayed with some boxes to fill.
    -4- If you have a lot of OID descriptions to add, it is more convenient to describe them in an XML document that conforms to our XML Schema for OIDs and submit this document through the web interface.
    Note: The description of an OID won't be visible until it is validated by the registrant of the superior node (if known) and/or the webmaster who are automatically informed by email.

  5. How to modify the description of an OID?
    If you want to update an OID that is described in the OID repository, please click on the "Modify this OID" hyperlink at the top-right of the web page that describes the OID or enter the OID in the following box:
         { }
    Your proposed modifications will have to be validated by the registrant of the OID being modified (if known), the registrant of the parent OID (if known) and the OID repository administrator (who will all be automatically informed by e-mail) before they get published.
    If an OID is misplaced in the OID tree and should be moved elsewhere in the tree, please use the "Comments" box at the bottom of the "Suggest a modification" web page to be displayed to explain where (and why) the OID should be moved.
    You can also mention in the "Comments" boc that an OID is a leaf in the OID tree (that is, child OIDs cannot be allocated), .

  6. How to delete an OID (or move it elsewhere in the OID tree)?
    According to ITU-T Rec. X.660 | ISO 9834-1, an OID shall not be deleted once it has been allocated by a Registration Authority. However there be the case that an OID is decribed in this OID repository but was never officially allocated by the Registration Authority for the parent OID (or is misplaced in the OID tree). In this case the OID has to be deleted from the OID repository (or moved elsewhere). To request the deletion (or to propose to move it elsewhere) please click on the "Modify this OID" hyperlink at the top-right of the web page that describes the OID or enter the OID in the following box:
         { }
    Use the "Comments" box at the bottom of the web page to be displayed to explain why the OID should be deleted (or moved elsewhere). Your suggestion will have to be validated by the registrant of the OID (if known), the registrant of the parent OID (if known) and the OID repository administrator (who will all be automatically informed by e-mail) before they get published.

  7. How does the OID repository provided on this website compare with Harald Alvestrand's repository?
    We get Harald's agreement to dump his repository and merge the data into our repository. This was done in June 2003 and our OID repository now encompasses Harald's registry.

  8. How to reference an OID description in this repository?
    The shortest and easiest means is to append the OID (whether it is in ASN.1 notation, dot notation or IRI notation) to the http://www.oid-info.com URL, e.g.:
  9. How many OIDs are currently described in this repository?
    There are more than 93,000 OID descriptions stored in our repository (exact number of OIDs in the repository). The repository is well alive and updated as often as necessary; statistics are available about the number of OIDs added to the repository (or updated) over the past 12 months. A (non-exhaustive) list of standards (and other documents that define OIDs) which have been captured in our repository is available in HTML and Microsoft Word format.

  10. How to get an OID assigned?
    The original intention of the ITU-T Rec. X.660 | ISO/IEC 9834 series was that anyone should be able to get an OID if they needed one. There are registrars from which it is easy and quite cheap (sometimes even free!) to have an OID assigned, such as:
  11. What decision needs be taken if a country wants a national Registration Authority for OIDs?
    Country arcs are the subsequent arcs of {iso(1) member-body(2)} and {joint-iso-itu-t(2) country(16)}. It seems that the former arc was deprecated in favour of the latter, except there may be differences in who administers them (usually the ISO National Body in the former case, and the ISO National Body or the representant of the ITU Member State or both in the latter case). But it makes more sense to have a unique Registration Authority (RA) for a given country: To achieve this, the best solution is for the ISO National Body and for the representant of the ITU Member State to agree together (as a national decision -- see next paragraph) that one of them is the RA for their country arc under {joint-iso-itu-t(2) country(16)}.
    According to ITU-T X.660 (2004) | ISO/IEC 9834-1:2004, A.4.5, "the values assigned to country-name arcs under {joint-iso-itu-t(2) country(16)} are the integer values of the numeric-3 codes of ISO 3166 (without leading zeros). The node identified by a country-name arc may be used to assign object identifiers within a country. The administration of this node is not prescribed by ITU-T Rec. X.660 | ISO/IEC 9834-1, but is is recommended that a single national RA be determined by the joint decision of the country's ITU-T Administration and ISO/IEC National Body. The assignment of registration responsibilities within a country is a national decision." (See also question 12 below.)
    This national decision doesn't need to be ratified by a formal joint Resolution of ITU-T SG17 and ISO/IEC JTC1/SC6 who are the subgroups responsible of ITU-T X.660 | ISO/IEC 9834-1. However, once an RA has been designated for a country OID, it is recommended that a letter be sent to inform both ITU-T SG17 and ISO/IEC JTC1/SC6, so that they can update the register of the superior OID, namely {joint-iso-itu-t(2) country(16)} (see example of such a letter).

  12. Are there guidelines or standards regarding subsequent arcs of a country arc?
    Country arcs are the subsequent arcs of {iso(1) member-body(2)} and {joint-iso-itu-t(2) country(16)}.
    The basic standard is of course ITU-T Rec. X.660 | ISO/IEC 9834-1. It might be worth having a look at ITU-T Rec. X.670: "Procedures for registration agents operating on behalf of organizations to register organization names subordinate to country names". There is no guidelines besides the fact that any registration authority needs to keep records according to the aforementioned standards.
    A good idea is probably to look at how other countries (such as Canada, Taiwan, USA) have organized their subsequent arcs.

  13. What is the Internet OID?
    The Internet OID is {iso(1) identified-organization(3) dod(6) internet(1)} or equivalently in dot notation 1.3.6.1.

  14. Where does the dot notation for OIDs come from?
    (from Harald Alvestrand's website)
    The dot notation is an IETF invention. The ASN.1 group thought it better to have a notation using spaces and braces, with optional text labels, so that 1.3.6.1 would become something like:
    {iso(1) org(3) dod(6) iana(1)}
    {1 3 6 1}
    {dod 1}
    or variants thereof.
    The IETF folks thought this was somewhat inconvenient, and decided to use a space-free notation. This is, among other things, spelled out in RFC 1778, section 2.15, but was in use long before that time.
    RFC 2252, section 4.1, eliminates the "ds.4.10" form.

  15. Why are top-level arcs restricted to three arcs numbered 0 to 2, and why are arcs beneath root arcs 0 and 1 restricted to fourty arcs numbered 0 to 39?
    This enables optimized encodings to be used in which the values of the top two arcs for all arcs under top-level arcs 0 and 1, and arcs 0 to 47 under top-level arc 2 encode in a single octet in an object identifier encoding (see the ITU-T Rec. X.690 series | ISO/IEC 8825 multi-part Standard).

  16. What do we call a registration tree (or object identifier tree)?
    In an open and international world such as the one of telecommunications and information technologies, you often need to be able to reference an "object" (see question 1) in a unique and universal way. The ASN.1 standard defines an object as being "a well-defined piece of information, definition or specification which requires a name in order to identify its use in an instance of communication".
    In general, an object is a class of information (for example, a file format), rather than an instance of such a class (for example, an individual file). It is thus the class of information (defined by some referenceable specification), rather than the piece of information itself, that is assigned a place in the tree.
    The naming structure that has been chosen is a tree structure that allows to name objects in a local or international context, without beeing limited either by the registration authority, nor by the number of objects they can register.

  17. What is the syntax of an OID?
    The naming pattern is therefore similar to the one of the Internet domains and subdomains. Each new node is associated with an optional (but recommended) identifier (for the legibility; it is a word beginning with a lowercase letter) and a mandatory number (that will be used for data transfers).
    Example: {joint-iso-itu-t(2) ds(5) attributeType(4) distinguishedName(49)} (see also question 14 for the dot notation)
    An object identifier is semantically an ordered list of object identifier components. Starting with the root of the object identifier tree, each object identifier component identifies an arc in the object identifier tree. The last object identifier component identifies an arc leading to a vertex to which an object has been assigned. It is this object which is identified by the object identifier.

  18. How is the entire registration tree managed?
    The management of the entire registration tree is accomplished by a process of delegation of authority. In this process the registration authority responsible for a given arc in the registration tree may partition that naming-domain. In doing so, it may or may not delegate the registration responsibility for the naming-domain formed by each partition to a subordinate Registration Authority. The naming of a partition does not necessarily imply authority to register objects under that partition. This delegation of registration responsibility can be applied repeatedly with a subordinate registration authority partitioning further the naming domain for which it is responsible and delegating responsibility for those partitions to registration authorities subordinate to it.
    The registration authority responsible for a given naming-domain must assign a name to the partition of that naming-domain that a given sub-authority will manage. The name assigned shall be globally unambiguous, and shall be concatenated as a prefix to all names assigned by that sub-authority. The repeated application of this process through a hierarchy of registration agents ensures the generation of unambiguous names.
    An organization, a standard or an automated facility can be the registration authority for more than one partition of a naming-domain (see also questions 11 and 12 for how country arcs are managed).

  19. Which features are offered by this repository?
    The description page for each OID offers the ability to:
    • have a synthetic graphical view of the tree (click on the and icons to fold and unfold arcs);
    • display the description of another OID (the "Go" button);
    • use the "remote control" to display the description of:
      • the father OID,
      • the previous or next brother OID,
      • the very first or very last brother OID, or
      • the first child OID;
    • submit a description of a child OID under the current OID (see also question 20): After putting down some information (description of the OID, its registrant...), the registrant of the OID (if known), the registrant of the parent OID (if known) and the OID repository administrator will be automatically asked by email to review and validate your submission. Note that the description page of the newly created OID will only be available after validation;
    • submit a description of a brother OID at the same level as the current OID (see also question 20);
    • propose modifications of the description of the current OID: these modifications will have to be validated by the registrant of the OID (if known), the registrant of the parent OID (if known) and the OID repository administrator (who will all be automatically informed by e-mail) before they get published;
    • do a quick search of the entire OID repository by searching for a particular string in all attributes;
    • do an advanced search of the entire OID repository by searching for a particular value for each description attribute or even by using regular expressions.
    Other features are available from the main page of the OID repository:
    • display the number of OIDs in the repository as well as statistics about how many OID descriptions were added or modified over the past 12 months;
    • add the description of a given OID (see also question 20);
    • submit many OIDs to the database by describing them in an XML file.

  20. What are the syntax rules to enter information about OIDs through the web interface?
    When adding information about an OID into the OID repository, non-ASCII characters such as accentuated letters are allowed in most fields ("Description", "Information", registrant "First name", "Last name" and "Address"). The software will replace them by their equivalent HTML code.
    The following HTML tags are allowed in the "Description", "Information" and "Address" fields: <a>, <b>, <br/>, <center>, <font>, <hr/>, <i>, <img>, <li>, <sub>, <sup>, <tt>, <ol> and <ul>. Use of <br> or <br/> is not mandatory to break lines because the software will replace by <br/> any newline character that appears in these fields.

  21. Which information is necessary to apply for an OID?
    According to subclause 8.2 f of ITU-T Rec. X.660 | ISO/IEC 9834-1, the registration record for an OID shall include at least:
    a) the name assigned to the object;
    b) the name and contact information of the organization that proposed the entry;
    c) the dates of submission/registration;
    d) the definition of the object (where the registration authority performs a technical role to check that the objet can be registered under its node).

  22. Which information is necessary to register a UUID as an OID?
    According to subclause 16.4.3.2 of ITU-T Rec. X.667 | ISO/IEC 9834-8, the record for registering a UUID as an OID shall include at least:
    a) Country in which the registering organization has its main headquarters;
    b) Name of organization, with country registration information if a registered company, charity, etc. or affiliation to a known international organization;
    c) Name and title, postal address, e-mail address, telephone and fax number for the contact point within the registering organization;
    d) Free-form information establishing the bona fides of the registering organization as a means to audit and remove spurious registrations (for example, the registering organization shall explain what use of the OID they will make, how the subsequent OIDs will be allocated, etc.);
    e) (Optionally) a URL that can be accessed to provide more information about the use of the UUID.
    In order to avoid spurious registrations, the registering organization shall understand that, being based on a UUID, the OID is a very long integer that can be handled by their application/system.

  23. What is the difference between the first and current Registration Authorities that appear in the description of some OIDs? What is their duty?
    A Registration Authority (RA) is responsible for allocating child arcs to the OID for which it manages. It ensures that an integer is used once among the subsequent arcs (child OIDs). As much as possible, it avoids the same identifier (beginning with a lowercase letter) being used for multiple sub-arcs. It also keeps a record of information (name of a contact person, postal address, telephone and fax numbers, email address, etc.) about the RA for each child OID and delegates its duty to each 'child' RA. Such information can be stored in the OID repository but it is important to understand that an OID first need to be officially allocated by an RA before it can be described on this website which is not an official RA, but a repository of information about existing OIDs.
    The first Registration Authority of an OID is the very first person or company to whom the OID was allocated by the RA of the superior OID. According to the ITU-T Rec. X.660 | ISO/IEC 9834-1 standard, the first RA can't be changed (if the responsibility is transfered to someone else, the information is recorded in the "Current Registration Authority" section, without changing the "First Registration Authority" section).
    By default, if the OID has recently been allocated, the Current RA is the First RA. So, if you are entering information in the OID repository, please fill only the "First Registration Authority" section, and don't copy the same information in the "Current Registration Authority" section).
    When someone or an organization takes over the duty from the First RA, the relevant information is indicated in the "Current Registration Authority" section without changing the "First Registration Authority" section.

  24. What constraints are imposed to OIDs used in SNMP MIBs (Management Information Bases)?
    The constraints are gathered in Sections 4.6.5, 4.6.6, and Appendix D of IETF RFC 4181 that was published in September 2005. That RFC makes references to RFC 2578 Sections 3.5, 3.6, 5.6, 7.10, and RFC 3416, Section 4.1. One example of a MIB module whose OID assignments follow the recommended scheme is the POWER-ETHERNET-MIB defined in RFC 3621.

  25. Is there a way to look up an OID in the OID repository from my web browser or email tool?
    - If you're using [Firefox Icon] Mozilla Firefox, an "OID resolver" add-on displays information about an OID when an IRI (e.g., oid:/x/y/z) or URN (e.g., urn:oid:x.y.z) notation is entered in the address bar at the top.
    - If you're using [Firefox Icon] Mozilla Firefox or [Mozilla Icon] Mozilla SeaMonkey (formerly known as Mozilla Application Suite) or [Mozilla Icon] Internet Explorer 7, an OpenSearch Plugin (a.k.a. search engine) allows to display information about an OID when an ASN.1, dot, URN or IRI notation is entered in the search bar at the top-right.
    - If you're using Mozilla Thunderbird, [Firefox Icon] Mozilla Firefox or [Mozilla Icon] Mozilla SeaMonkey (formerly known as Mozilla Application Suite), the DictionarySearch add-on is easy to configure so that you can display information about an OID by right-clicking on its selection:
    • install the DictionarySearch extension corresponding to your tool from http://dictionarysearch.mozdev.org;
    • in the "Tools" menu of your tool, select the "Extensions" item;
    • highlight the line for DictionarySearch, then click on the "Options" button;
    • add a new Dictionary with the following information (this will display the description of the selected OIDin dot notation; it doesn't work well for a selected OID in ASN.1 notation because the closing parentheses are removed for whatever reason):
      Text: Search for OID "$"
      Access key: O
      URL: http://asn1.elibel.tm.fr/cgi-bin/display?oid=$&action=display
    • This other new "Dictionary" may also be useful (it will display a tree for the selected OID in dot notation):
      Text: Display tree for OID "$"
      Access key: T
      URL: http://asn1.elibel.tm.fr/cgi-bin/display?oid=$&action=tree
    - If you're using [Firefox Icon] Mozilla Firefox, the "URN Support" add-on from SHIMODA Hiroshi redirects a URN of the form urn:oid:x.y.z to the description of this OID in this OID repository. Note: This add-on is not compatible with the "OID resolver" add-on mentioned in the first bullet above.
    - See also question 8.

  26. What is a leaf OID?
    This is not a standardized concept but in case an OID is a leaf in the OID tree, no child OIDs can be allocated under that OID. The 'leaf' status can be stored in the OID repository so that the system doesn't accept the creation of child OIDs. The 'leaf' status is also mentioned on the web page that describes an OID (see example). To report that an OID is a leaf please suggest a modification for this OID and use the "Comments" box at the bottom of the "Suggest a modification" web page..

  27. What is a orphan OID?
    This is not a standardized concept but this term is used to describe an OID that is described in the OID repository, but some of the ascending (parent) OIDs are not described in the OID repository. This does not mean that these unknown ascending OIDs do not exist (actually they do exist because an OID can only be allocated by the Registration Authority of its parent OID). However the user who submitted the description of this OID has no knowledge of how to describe these ascending OIDs.
    This is useful in cases such as:
    - you have found the description of an OID somewhere on the web or in a document, but you don't know how to describe all arcs along the path;
    - you have a bunch of OIDs to submit to the OID repository, so you can submit them in any order because there is no obligation to submit the father OID first.
    Orphan OIDs are not visible when one walks down the OID tree. However, their description is displayed when one asks for the description of a particular OID. Moreover, they will automatically be visible as soon as a description of the missing ascending OIDs is submitted to the OID repository.
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