Encyclopedia of Computer Science and Technology

158 documentation of program codewill treat this as the default and not require that it be typed.ftp:// can be used to access ftp servers via the Web. Finally,a URL must include the path to the directory that actuallycontains the HTML document or other resource, as wellas its filename. Thus a complete address for a hypotheticaluser’s home page might be:http://www.BigUniversity.edu/users/tomr/index.htmlInternal AddressingWhen a Web user types such an address, the Web browserconnects to a nearby name server. This program translatesthe name into an IP (Internet Protocol) address. Theaddress consists of four 8-bit numbers called tuples, separatedby periods. For example, the domain name www.well.com currently translates to 208.178.101.2. The first numberrepresents one of five classes of networks, with thefirst three classes (A-C) organized according to the numberand size of networks and D and E being reserved for oneto-many“broadcast” transmissions and experimentationrespectively.To obtain a domain name, a person or organizationcontacts one of several registration services accredited byICANN (the nonprofit Internet Corporation for assignedNames and Numbers). Each name must be unique. Considerablelegal disputation has occurred when someonenot connected with a company has registered a domaincontaining that company’s name. The tremendous growthof e-commerce has made distinctive or easy-to-rememberdomain names a scarce and valuable commodity. Foreseeingthis, some speculators bought up attractive domains inthe hope (sometimes realized) of selling them to corporationsat a huge profit. Anti–“domain squatting” laws werepassed in reaction. In other cases, disgruntled employees orconsumers have registered domains for Web sites critical ofmajor corporations such as airlines and telephone companies.In the courts, this pits the right of free speech againstthe right of a company to control the use of its name.Expanding the SystemThe expansion of the Internet has strained the capacity ofthe existing DNS. The shortage of “name space” is beingaddressed by the release of IP Version 6, which replaces the32-bit addresses with 128-bit ones. In addition, in November2000 ICANN announced the creation of seven new topleveldomains: .aero (air transport), .biz (business), .coop(cooperatives), .info (general-purpose), .museum (museums),.name (personal sites), and .pro (professionals suchas lawyers, accountants, and physicians). However, the situationis muddled by the existence of competing proposalsand the use of unofficial DNS systems that provide theirown domains (but require special software for access, sincethey are not recognized by regular DNS servers).Perhaps a more fundamental issue is the adopting ofa system designed by English speakers to a world thatincreasingly seeks international access and standards (seeinternationalization). The problem is how to meet localneeds without creating new barriers through incompatibleaddressing schemes. The proposal being implemented as ofthe mid-2000s is called Internationalizing Domain Namesin Applications (IDNA). This standard includes an algorithmby which address labels written using the many charactersets and diacritical marks in the world’s languages(as rendered in Unicode) can be translated to the standardASCII characters used by the existing DNS (see charactersand strings).Further ReadingAlbitz, Paul, and Cricket Liu. DNS and BIND, 4th ed. Sebastopol,Calif.: O’Reilly, 2001.ICANN (Internet Corporation for Assigned Names and Numbers).Available online. URL: http://www.icann.org/. AccessedAugust 14, 2007.“Internationalization of Domain Names: A History of Technology.”Internet Society. www.isoc.org/pubpolpillar/docs/i18n-dnschronology.pdf.Accessed July 10, 2007.InterNIC. Available online. URL: http://www.internic.net/. AccessedAugust 14, 2007.InterNIC Registry WhoIs [domain look-up]. Available online.URL: http://www.internic.net/whois.html. Accessed August14, 2007.documentation of program codeComputer system documentation can be divided into twomain categories based upon the intended audience. Manualsand training materials for users focus on explaininghow to use the program’s features to meet the user’s needs(see documentation, user). This entry, however, focuseson the creation of documentation for programmers and othersinvolved in software development and maintenance (seealso technical writing).Software documentation can consist of commentsdescribing the operation of a line or section of code. Earlyprogramming with its reliance on punched cards had onlyminimal facilities for incorporating comments. (Some of theproponents of COBOL thought that the language’s Englishlikesyntax would make additional documentation unnecessary.Like the similar claim that trained programmerswould no longer be needed, the reality proved otherwise.)After the switch from punchcard input to the use ofkeyboards, adding comments became easier. For example, acomment in C looks like this:printf(“Hello, world\n”);/* Display the traditional message */while C++ uses comments in this form:cout