The

JANET Janet may refer to: Names * Janet (given name) * Janet (French singer) (1939–2011) Surname * Charles Janet (1849–1932), French engineer, inventor and biologist, known for the Left Step periodic table * Jules Janet (1861–1945), French psych ...

NRS (''Name Registration Scheme'') was a pseudo-hierarchical naming scheme used on

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English, ...

academic and research networks in the 1980s. It used a

reverse domain name notation Reverse domain name notation (or reverse-DNS) is a naming convention for components, packages, types or file names used by a programming language, system or framework. Reverse-DNS strings are based on registered domain names, with the order of the ...

History

It was proposed in 1983 and used until the superficially similar Internet

Domain Name System The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned to ...

was fully adopted.

Structure

The NRS "

second-level domains In the Domain Name System (DNS) hierarchy, a second-level domain (SLD or 2LD) is a domain that is directly below a top-level domain (TLD). For example, in , is the second-level domain of the TLD. Second-level domains commonly refer to the organ ...

" consisted of (JANET academic and scientific sites), (commercial) and (

Ministry of Defence {{unsourced, date=February 2021 A ministry of defence or defense (see spelling differences), also known as a department of defence or defense, is an often-used name for the part of a government responsible for matters of defence, found in states ...

). Any organisations not falling into these categories were given their own "second-level" name, e.g. (

British Library The British Library is the national library of the United Kingdom and is one of the largest libraries in the world. It is estimated to contain between 170 and 200 million items from many countries. As a legal deposit library, the British ...

) or (

National Engineering Laboratory The National Engineering Laboratory (NEL) was originally one of several large government-funded public research laboratories in the UK, staffed by scientists and engineers of the Scientific Civil Service. Other such laboratories include the Nat ...

). All NRS names had both a ''standard'' (long) and ''abbreviated'' (up to 18 characters) form. For example, was the less widely used standard equivalent of the abbreviated name . For email, interoperability between the " Grey Book" email addressing style of and ARPA and USENET addresses of the style was achieved by way of mail gateway at

University College London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = ...

Comparison with DNS

A principal difference with the

was that the order of significance began with the most significant part (so called

big-endian In computing, endianness, also known as byte sex, is the order or sequence of bytes of a word of digital data in computer memory. Endianness is primarily expressed as big-endian (BE) or little-endian (LE). A big-endian system stores the most sig ...

addresses). Also, NRS names were canonically written in upper case. For example, the

University of Cambridge , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

had the NRS name , whereas its DNS domain is . After Internet

top-level domains A top-level domain (TLD) is one of the domains at the highest level in the hierarchical Domain Name System of the Internet after the root domain. The top-level domain names are installed in the root zone of the name space. For all domains in ...

were introduced from 1984, confusion was caused when the least significant part of an Internet address matched the most significant part of an NRS address and vice versa. The ccTLD "

.cs .cs was for several years the country code top-level domain (ccTLD) for Czechoslovakia. However, the country split into the Czech Republic and Slovakia in 1993, and the two new countries were soon assigned their own ccTLDs: .cz and .sk respec ...

" for

Czechoslovakia , rue, Чеськословеньско, , yi, טשעכאסלאוואקיי, , common_name = Czechoslovakia , life_span = 1918–19391945–1992 , p1 = Austria-Hungary , image_p1 ...

came into use around 1990-2 until 1995. The classic joke was that e-mail intended for UK universities ended up in Czechoslovakia, since many JANET e-mail addresses were of the form ''universityname'', where "CS" stood for Computer Science (department). Another significant difference from the DNS was the concept of context to name lookups, e.g. 'mail' or 'file transfer'. This made the NRS more sophisticated than the DNS, permitting overloading of names.

Legacy

JANET transitioned to using

Internet protocols The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...

in 1991, and by 1994 the DNS had become the de facto standard for domain names on JANET. The final mail gateway was taken out of service by the end of 1997. The one remaining legacy of the NRS is the convention of using

.uk .uk is the Internet country code top-level domain (ccTLD) for the United Kingdom. It was first registered in July 1985, seven months after the original generic top-level domains such as .com and the first country code after .us. , it is the fift ...

for the Internet

country code top-level domain A country code top-level domain (ccTLD) is an Internet top-level domain generally used or reserved for a country, sovereign state, or dependent territory identified with a country code. All ASCII ccTLD identifiers are two letters long, and all t ...

(ccTLD), rather than

.gb .gb is a reserved Internet country code top-level domain (ccTLD) for the United Kingdom. The domain was introduced with RFC 920 in October 1984 that set out the creation of ccTLD generally using country codes derived from the corresponding two ...

as specified by

ISO 3166 ISO 3166 is a standard published by the International Organization for Standardization (ISO) that defines codes for the names of countries, dependent territories, special areas of geographical interest, and their principal subdivisions (e.g., ...

. The UK was the only country with a pre-existing national standard.

References

Sources