71-540: Chainz .cryptoid .info /nmc / Namecoin ( Abbreviation : NMC ; sign : N {\displaystyle \mathbb {N} } ) is a cryptocurrency originally forked from bitcoin software. It uses proof-of-work algorithm. Like bitcoin, it is limited to 21 million coins. Namecoin can store data within its own blockchain transaction database . The original proposal for Namecoin called for Namecoin to insert data into bitcoin's blockchain directly. Anticipating scaling difficulties with this approach,
142-446: A label and zero or more resource records (RR), which hold information associated with the domain name. The domain name itself consists of the label, concatenated with the name of its parent node on the right, separated by a dot. The tree sub-divides into zones beginning at the root zone . A DNS zone may consist of as many domains and subdomains as the zone manager chooses. DNS can also be partitioned according to class where
213-480: A "com" server, and finally an "example.com" server. Name servers in delegations are identified by name, rather than by IP address. This means that a resolving name server must issue another DNS request to find out the IP address of the server to which it has been referred. If the name given in the delegation is a subdomain of the domain for which the delegation is being provided, there is a circular dependency . In this case,
284-516: A "hard space" ( non-breaking space ) and the amount: and for texts in Bulgarian , Croatian , Czech , Danish , Dutch , Estonian , Finnish , French , German , Greek , Hungarian , Italian , Lithuanian , Polish , Portuguese , Romanian , Slovak , Slovene , Spanish , and Swedish the order is reversed; the amount is followed by a non-breaking space and the ISO ;4217 code: As illustrated,
355-408: A cache of data. An authoritative name server can either be a primary server or a secondary server. Historically the terms master/slave and primary/secondary were sometimes used interchangeably but the current practice is to use the latter form. A primary server is a server that stores the original copies of all zone records. A secondary server uses a special automatic updating mechanism in
426-416: A combination of these methods. In a non-recursive query , a DNS resolver queries a DNS server that provides a record either for which the server is authoritative, or it provides a partial result without querying other servers. In case of a caching DNS resolver , the non-recursive query of its local DNS cache delivers a result and reduces the load on upstream DNS servers by caching DNS resource records for
497-728: A compromise between five competing proposals of solutions to Paul Mockapetris . Mockapetris instead created the Domain Name System in 1983 while at the University of Southern California . The Internet Engineering Task Force published the original specifications in RFC 882 and RFC 883 in November 1983. These were updated in RFC 973 in January 1986. In 1984, four UC Berkeley students, Douglas Terry, Mark Painter, David Riggle, and Songnian Zhou, wrote
568-437: A consensus. In the same month, OpenNIC was advised to drop support for .bit namespace owing to security concerns of Namecoin and PRISM Break developers. In July 2019, OpenNIC again voted on dropping the .bit namespace, citing "numerous problems with support of NameCoin domains" and recent animosity between the two projects. The vote passed. Namecoin developer Jeremy Rand welcomed the move, thanking OpenNIC and describing it as
639-455: A corresponding free-software implementation and a supporting extension for Firefox . In October 2013, Michael Gronager, main developer of libcoin, found a security issue in the Namecoin protocol, which allowed modifying foreign names. It was successfully fixed in a short timeframe and was never exploited, except for bitcoin.bit as a proof-of-concept. Namecoin was also mentioned by ICANN in
710-399: A dataset from a reliable source. Assuming the resolver has no cached records to accelerate the process, the resolution process starts with a query to one of the root servers. In typical operation, the root servers do not answer directly, but respond with a referral to more authoritative servers, e.g., a query for "www.wikipedia.org" is referred to the org servers. The resolver now queries
781-580: A general purpose database, the DNS has also been used in combating unsolicited email (spam) by storing a real-time blackhole list (RBL). The DNS database is traditionally stored in a structured text file, the zone file , but other database systems are common. The Domain Name System originally used the User Datagram Protocol (UDP) as transport over IP. Reliability, security, and privacy concerns spawned
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#1732858226825852-581: A hypothetical system called BitDNS and generalizing bitcoin. Gavin Andresen and Satoshi Nakamoto joined the discussion in the BitcoinTalk forum and supported the idea of BitDNS, and a reward for implementing BitDNS was announced on the forum in December 2010. On block 19200 Namecoin activated the merged mining upgrade to allow mining of Bitcoin and Namecoin simultaneously, instead of having to choose between one or
923-618: A list of all currently pegged currencies. Despite having no presence or status in the standard, three letter acronyms that resemble ISO 4217 coding are sometimes used locally or commercially to represent de facto currencies or currency instruments. The following non-ISO codes were used in the past. Minor units of currency (also known as currency subdivisions or currency subunits) are often used for pricing and trading stocks and other assets, such as energy, but are not assigned codes by ISO 4217. Two conventions for representing minor units are in widespread use: A third convention
994-490: A path, with the namespace preceding the name of the record. The key d/example signifies a record stored in the DNS namespace d with the name example and corresponds to the record for the example.bit website. The content of d/example is expected to conform to the DNS namespace specification. As of 2015, the fee for a record was 0.01 NMC and records expired after 36000 blocks (~200 days) unless updated or renewed. .bit
1065-407: A period of time after an initial response from upstream DNS servers. In a recursive query , a DNS resolver queries a single DNS server, which may in turn query other DNS servers on behalf of the requester. For example, a simple stub resolver running on a home router typically makes a recursive query to the DNS server run by the user's ISP . A recursive query is one for which the DNS server answers
1136-588: A public report as the most well-known example of distributing control and privacy in DNS . A 2015 study found that of the 120,000 domain names registered on Namecoin, only 28 were in use. In December 2018, a proposal was tabled on the OpenNIC mailing list to drop support for Namecoin .bit domains., citing Spamhaus ' (and by extension other antivirus software ) blocking of several of their servers owing to spread of malware from some .bit domains, as well as concerns about potential child pornography. The vote did not reach
1207-503: A result, the list of codes must be updated from time to time. The ISO 4217 maintenance agency is responsible for maintaining the list of codes. In the case of national currencies, the first two letters of the alpha code are the two letters of the ISO ;3166-1 alpha-2 country code and the third is usually the initial of the currency's main unit. So Japan 's currency code is JPY : "JP" for Japan and "Y" for yen . This eliminates
1278-469: A service's location on the network to change without affecting the end users, who continue to use the same hostname. Users take advantage of this when they use meaningful Uniform Resource Locators ( URLs ) and e-mail addresses without having to know how the computer actually locates the services. An important and ubiquitous function of the DNS is its central role in distributed Internet services such as cloud services and content delivery networks . When
1349-476: A shared proof-of-work system was proposed to secure new cryptocurrencies with different use cases . Namecoin's flagship use case is the censorship-resistant top level domain .bit , which is functionally similar to .com or .net domains but is independent of the Internet Corporation for Assigned Names and Numbers , the main governing body for domain names. In practice, the top level domain
1420-477: A type of error called a "lame delegation" or "lame response". Domain name resolvers determine the domain name servers responsible for the domain name in question by a sequence of queries starting with the right-most (top-level) domain label. For proper operation of its domain name resolver, a network host is configured with an initial cache ( hints ) of the known addresses of the root name servers. The hints are updated periodically by an administrator by retrieving
1491-455: A user accesses a distributed Internet service using a URL, the domain name of the URL is translated to the IP address of a server that is proximal to the user. The key functionality of the DNS exploited here is that different users can simultaneously receive different translations for the same domain name, a key point of divergence from a traditional phone-book view of the DNS. This process of using
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#17328582268251562-404: Is a top-level domain , created outside the commonly used Domain Name System , and is not sanctioned by ICANN. The .bit domain is served via Namecoin infrastructure, which acts as a decentralized domain name system. Proposed potential uses for Namecoin besides domain name registration include notary / timestamp systems. In September 2010, a discussion was started in the BitcoinTalk forum about
1633-486: Is facilitated by the ISO 3166 rule that no official country code beginning with X will ever be assigned. The inclusion of EU (denoting the European Union ) in the ISO 3166-1 reserved codes list allows the euro to be coded as EUR rather than assigned a code beginning with X, even though it is a supranational currency. ISO 4217 also assigns a three-digit numeric code to each currency. This numeric code
1704-489: Is known as the LDH rule (letters, digits, hyphen). Domain names are interpreted in a case-independent manner. Labels may not start or end with a hyphen. An additional rule requires that top-level domain names should not be all-numeric. The limited set of ASCII characters permitted in the DNS prevented the representation of names and words of many languages in their native alphabets or scripts. To make this possible, ICANN approved
1775-484: Is only achieved with at least 6 labels (counting the last null label). Although no technical limitation exists to prevent domain name labels from using any character that is representable by an octet, hostnames use a preferred format and character set. The characters allowed in labels are a subset of the ASCII character set, consisting of characters a through z , A through Z , digits 0 through 9 , and hyphen. This rule
1846-399: Is served by the root name servers , the servers to query when looking up ( resolving ) a TLD . An authoritative name server is a name server that only gives answers to DNS queries from data that have been configured by an original source, for example, the domain administrator or by dynamic DNS methods, in contrast to answers obtained via a query to another name server that only maintains
1917-591: Is similar to the second one but uses an upper-case letter, e.g. ZAC for the South African Cent. Cryptocurrencies have not been assigned an ISO 4217 code. However, some cryptocurrencies and cryptocurrency exchanges use a three-letter acronym that resemble an ISO 4217 code. DNS Early research and development: Merging the networks and creating the Internet: Commercialization, privatization, broader access leads to
1988-405: Is used by a handful of functional websites. As of 2019, OpenNIC no longer supports the .bit domain. A peer-to-peer network similar to handles Namecoin's transactions, balances and issuance through a based proof-of-work scheme (they are issued when a small enough hash value is found, at which point a block is created). Each Namecoin record consists of a name and a value. Each name is actually
2059-691: Is usually the same as the numeric code assigned to the corresponding country by ISO 3166-1 . For example, USD ( United States dollar ) has numeric code 840 which is also the ISO 3166-1 code for "US" (United States). The following is a list of active codes of official ISO 4217 currency names as of 1 January 2024 . In the standard the values are called "alphabetic code", "numeric code", "minor unit", and "entity". According to UN/CEFACT recommendation 9, paragraphs 8–9 ECE/TRADE/203, 1996: A number of currencies had official ISO 4217 currency codes and currency names until their replacement by another currency. The table below shows
2130-532: The Internationalizing Domain Names in Applications (IDNA) system, by which user applications, such as web browsers, map Unicode strings into the valid DNS character set using Punycode . In 2009, ICANN approved the installation of internationalized domain name country code top-level domains ( ccTLD s) . In addition, many registries of the existing top-level domain names ( TLD s ) have adopted
2201-478: The top-level domain ; for example, the domain name www.example.com belongs to the top-level domain com . The hierarchy of domains descends from right to left; each label to the left specifies a subdivision, or subdomain of the domain to the right. For example, the label example specifies a subdomain of the com domain, and www is a subdomain of example.com. This tree of subdivisions may have up to 127 levels. A label may contain zero to 63 characters, because
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2272-404: The " Authoritative Answer " ( AA ) bit in its responses. This flag is usually reproduced prominently in the output of DNS administration query tools, such as dig , to indicate that the responding name server is an authority for the domain name in question. When a name server is designated as the authoritative server for a domain name for which it does not have authoritative data, it presents
2343-489: The "right decision". ISO 4217#Cryptocurrencies ISO 4217 is a standard published by the International Organization for Standardization (ISO) that defines alpha codes and numeric codes for the representation of currencies and provides information about the relationships between individual currencies and their minor units. This data is published in three tables: The first edition of ISO 4217
2414-526: The ARPANET. Elizabeth Feinler developed and maintained the first ARPANET directory. Maintenance of numerical addresses, called the Assigned Numbers List, was handled by Jon Postel at the University of Southern California 's Information Sciences Institute (ISI), whose team worked closely with SRI. Addresses were assigned manually. Computers, including their hostnames and addresses, were added to
2485-462: The DNS database are for start of authority ( SOA ), IP addresses ( A and AAAA ), SMTP mail exchangers (MX), name servers (NS), pointers for reverse DNS lookups (PTR), and domain name aliases (CNAME). Although not intended to be a general purpose database, DNS has been expanded over time to store records for other types of data for either automatic lookups, such as DNSSEC records, or for human queries such as responsible person (RP) records. As
2556-401: The DNS protocol in communication with its primary to maintain an identical copy of the primary records. Every DNS zone must be assigned a set of authoritative name servers. This set of servers is stored in the parent domain zone with name server (NS) records. An authoritative server indicates its status of supplying definitive answers, deemed authoritative , by setting a protocol flag, called
2627-468: The DNS to assign proximal servers to users is key to providing faster and more reliable responses on the Internet and is widely used by most major Internet services. The DNS reflects the structure of administrative responsibility on the Internet. Each subdomain is a zone of administrative autonomy delegated to a manager. For zones operated by a registry , administrative information is often complemented by
2698-456: The IDNA system, guided by RFC 5890, RFC 5891, RFC 5892, RFC 5893. The Domain Name System is maintained by a distributed database system, which uses the client–server model . The nodes of this database are the name servers . Each domain has at least one authoritative DNS server that publishes information about that domain and the name servers of any domains subordinate to it. The top of the hierarchy
2769-430: The IP address spaces . The Domain Name System maintains the domain name hierarchy and provides translation services between it and the address spaces. Internet name servers and a communication protocol implement the Domain Name System. A DNS name server is a server that stores the DNS records for a domain; a DNS name server responds with answers to queries against its database. The most common types of records stored in
2840-488: The ISO currency codes of former currencies and their common names (which do not always match the ISO 4217 names). That table has been introduced end 1988 by ISO. The 2008 (7th) edition of ISO 4217 says the following about minor units of currency: Requirements sometimes arise for values to be expressed in terms of minor units of currency. When this occurs, it is necessary to know the decimal relationship that exists between
2911-402: The Internet, and increase performance in end-user applications, the Domain Name System supports DNS cache servers which store DNS query results for a period of time determined in the configuration ( time-to-live ) of the domain name record in question. Typically, such caching DNS servers also implement the recursive algorithm necessary to resolve a given name starting with the DNS root through to
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2982-704: The United States dollar and the Bahraini dinar , for which the column headed "Minor unit" shows "2" and "3", respectively. As of 2021 , two currencies have non-decimal ratios, the Mauritanian ouguiya and the Malagasy ariary ; in both cases the ratio is 5:1. For these, the "Minor unit" column shows the number "2". Some currencies, such as the Burundian franc , do not in practice have any minor currency unit at all. These show
3053-543: The authoritative name servers of the queried domain. With this function implemented in the name server, user applications gain efficiency in design and operation. The combination of DNS caching and recursive functions in a name server is not mandatory; the functions can be implemented independently in servers for special purposes. Internet service providers typically provide recursive and caching name servers for their customers. In addition, many home networking routers implement DNS caches and recursion to improve efficiency in
3124-466: The computer. Computers at educational institutions would have the domain edu , for example. She and her team managed the Host Naming Registry from 1972 to 1989. By the early 1980s, maintaining a single, centralized host table had become slow and unwieldy and the emerging network required an automated naming system to address technical and personnel issues. Postel directed the task of forging
3195-487: The currencies, instead of translated currency names or ambiguous currency symbols . ISO 4217 alpha codes are used on airline tickets and international train tickets to remove any ambiguity about the price. In 1973, the ISO Technical Committee 68 decided to develop codes for the representation of currencies and funds for use in any application of trade, commerce or banking. At the 17th session (February 1978),
3266-478: The currency concerned and its minor unit. This information has therefore been included in this International Standard and is shown in the column headed "Minor unit" in Tables A.1 and A.2; "0" means that there is no minor unit for that currency, whereas "1", "2" and "3" signify a ratio of 10:1, 100:1 and 1000 :1 respectively. The names of the minor units are not given. Examples for the ratios of 100 :1 and 1000 :1 include
3337-438: The delegation for example.org. The glue records are address records that provide IP addresses for ns1.example.org. The resolver uses one or more of these IP addresses to query one of the domain's authoritative servers, which allows it to complete the DNS query. A common approach to reduce the burden on DNS servers is to cache the results of name resolution locally or on intermediary resolver hosts. Each DNS query result comes with
3408-738: The first Unix name server implementation for the Berkeley Internet Name Domain, commonly referred to as BIND . In 1985, Kevin Dunlap of DEC substantially revised the DNS implementation. Mike Karels , Phil Almquist, and Paul Vixie then took over BIND maintenance. Internet Systems Consortium was founded in 1994 by Rick Adams , Paul Vixie , and Carl Malamud , expressly to provide a home for BIND development and maintenance. BIND versions from 4.9.3 onward were developed and maintained by ISC, with support provided by ISC's sponsors. As co-architects/programmers, Bob Halley and Paul Vixie released
3479-453: The first production-ready version of BIND version 8 in May 1997. Since 2000, over 43 different core developers have worked on BIND. In November 1987, RFC 1034 and RFC 1035 superseded the 1983 DNS specifications. Several additional Request for Comments have proposed extensions to the core DNS protocols. The domain name space consists of a tree data structure . Each node or leaf in the tree has
3550-433: The length is only allowed to take 6 bits. The null label of length zero is reserved for the root zone. The full domain name may not exceed the length of 253 characters in its textual representation (or 254 with the trailing dot). In the internal binary representation of the DNS this maximum length of 253 requires 255 octets of storage, as it also stores the length of the first of many labels and adds last null byte. 255 length
3621-422: The local network. The client side of the DNS is called a DNS resolver. A resolver is responsible for initiating and sequencing the queries that ultimately lead to a full resolution (translation) of the resource sought, e.g., translation of a domain name into an IP address. DNS resolvers are classified by a variety of query methods, such as recursive , non-recursive , and iterative . A resolution process may use
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#17328582268253692-476: The modern Internet: Examples of Internet services: The Domain Name System ( DNS ) is a hierarchical and distributed name service that provides a naming system for computers , services, and other resources on the Internet or other Internet Protocol (IP) networks. It associates various information with domain names ( identification strings ) assigned to each of the associated entities. Most prominently, it translates readily memorized domain names to
3763-408: The name server and IP address. For example, if the authoritative name server for example.org is ns1.example.org, a computer trying to resolve www.example.org first resolves ns1.example.org. As ns1 is contained in example.org, this requires resolving example.org first, which presents a circular dependency. To break the dependency, the name server for the top level domain org includes glue along with
3834-409: The name server providing the delegation must also provide one or more IP addresses for the authoritative name server mentioned in the delegation. This information is called glue . The delegating name server provides this glue in the form of records in the additional section of the DNS response, and provides the delegation in the authority section of the response. A glue record is a combination of
3905-521: The number "0", as with currencies whose minor units are unused due to negligible value. The ISO standard does not regulate either the spacing, prefixing or suffixing in usage of currency codes. The style guide of the European Union 's Publication Office declares that, for texts issued by or through the Commission in English , Irish , Latvian , and Maltese , the ISO 4217 code is to be followed by
3976-613: The numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols . The Domain Name System has been an essential component of the functionality of the Internet since 1985. The Domain Name System delegates the responsibility of assigning domain names and mapping those names to Internet resources by designating authoritative name servers for each domain. Network administrators may delegate authority over subdomains of their allocated name space to other name servers. This mechanism provides distributed and fault-tolerant service and
4047-423: The official currency names. In some cases, the third letter of the alpha code is not the initial letter of a currency unit name. There may be a number of reasons for this: In addition to codes for most active national currencies ISO 4217 provides codes for "supranational" currencies, procedural purposes, and several things which are "similar to" currencies: The use of an initial letter "X" for these purposes
4118-508: The order is determined not by the currency but by the native language of the document context. The US dollar has two codes assigned: USD and USN ("US dollar next day"). The USS (same day) code is not in use any longer, and was removed from the list of active ISO 4217 codes in March 2014. A number of active currencies do not have an ISO 4217 code, because they may be: These currencies include: See Category:Fixed exchange rate for
4189-534: The other; this fixed the issue of miners jumping from one blockchain to another when the profitability becomes favorable in the former. Two years later, in June 2013, NameID was launched. NameID allows to associate profile information with identities on the Namecoin blockchain, and an OpenID provider to allow logging into existing websites with Namecoin identities. The main site itself is accompanied by an open protocol for password-less authentication with Namecoin identities,
4260-532: The primary file by contacting the SRI Network Information Center (NIC), directed by Feinler, via telephone during business hours. Later, Feinler set up a WHOIS directory on a server in the NIC for retrieval of information about resources, contacts, and entities. She and her team developed the concept of domains. Feinler suggested that domains should be based on the location of the physical address of
4331-580: The problem caused by the names dollar , franc , peso , and pound being used in dozens of countries, each having significantly differing values. While in most cases the ISO code resembles an abbreviation of the currency's full English name, this is not always the case, as currencies such as the Algerian dinar , Aruban florin , Cayman dollar , renminbi , sterling , and the Swiss franc have been assigned codes which do not closely resemble abbreviations of
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#17328582268254402-402: The query completely by querying other name servers as needed. In typical operation, a client issues a recursive query to a caching recursive DNS server, which subsequently issues non-recursive queries to determine the answer and send a single answer back to the client. The resolver, or another DNS server acting recursively on behalf of the resolver, negotiates use of recursive service using bits in
4473-404: The query headers. DNS servers are not required to support recursive queries. The iterative query procedure is a process in which a DNS resolver queries a chain of one or more DNS servers. Each server refers the client to the next server in the chain, until the current server can fully resolve the request. For example, a possible resolution of www.example.com would query a global root server, then
4544-472: The registry's RDAP and WHOIS services. That data can be used to gain insight on, and track responsibility for, a given host on the Internet. Using a simpler, more memorable name in place of a host's numerical address dates back to the ARPANET era. The Stanford Research Institute (now SRI International ) maintained a text file named HOSTS.TXT that mapped host names to the numerical addresses of computers on
4615-523: The related UN / ECE Group of Experts agreed that the three-letter alphabetic codes for International Standard ISO 4217, "Codes for the representation of currencies and funds", would be suitable for use in international trade. Over time, new currencies are created and old currencies are discontinued. Such changes usually originate from the formation of new countries, treaties between countries on shared currencies or monetary unions, or redenomination from an existing currency due to excessive inflation. As
4686-516: The root servers, and as a result, root name servers actually are involved in only a relatively small fraction of all requests. In theory, authoritative name servers are sufficient for the operation of the Internet. However, with only authoritative name servers operating, every DNS query must start with recursive queries at the root zone of the Domain Name System and each user system would have to implement resolver software capable of recursive operation. To improve efficiency, reduce DNS traffic across
4757-629: The separate classes can be thought of as an array of parallel namespace trees. Administrative responsibility for any zone may be divided by creating additional zones. Authority over the new zone is said to be delegated to a designated name server. The parent zone ceases to be authoritative for the new zone. The definitive descriptions of the rules for forming domain names appear in RFC 1035, RFC 1123, RFC 2181, and RFC 5892. A domain name consists of one or more parts, technically called labels , that are conventionally concatenated , and delimited by dots, such as example.com. The right-most label conveys
4828-423: The servers referred to, and iteratively repeats this process until it receives an authoritative answer. The diagram illustrates this process for the host that is named by the fully qualified domain name "www.wikipedia.org". This mechanism would place a large traffic burden on the root servers, if every resolution on the Internet required starting at the root. In practice caching is used in DNS servers to off-load
4899-592: The use of the Transmission Control Protocol (TCP) as well as numerous other protocol developments. An often-used analogy to explain the DNS is that it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses. For example, the hostname www.example.com within the domain name example.com translates to the addresses 93.184.216.34 ( IPv4 ) and 2606:2800:220:1:248:1893:25c8:1946 ( IPv6 ). The DNS can be quickly and transparently updated, allowing
4970-462: Was designed to avoid a single large central database. In addition, the DNS specifies the technical functionality of the database service that is at its core. It defines the DNS protocol, a detailed specification of the data structures and data communication exchanges used in the DNS, as part of the Internet protocol suite . The Internet maintains two principal namespaces , the domain name hierarchy and
5041-499: Was published in 1978. The tables, history and ongoing discussion are maintained by SIX Group on behalf of ISO and the Swiss Association for Standardization . The ISO 4217 code list is used in banking and business globally. In many countries, the ISO 4217 alpha codes for the more common currencies are so well known publicly that exchange rates published in newspapers or posted in banks use only these to delineate
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