Indonesian names and naming customs reflect the multicultural and multilingual nature of the over 17,000 islands in the Indonesian archipelago. The world's fourth most populous nation, Indonesia is home to more than 1300 ethnic groups, each with their own culture, custom, and language. The Javanese are the largest single group, comprising around 40 percent of Indonesia's total population. Honorifics General In Indonesia, ranks and professional titles are used. It is also customary to use Pak, Bapak, or Saudara to address men and Bu, Ibu, or Saudari to address women. Pak and Bapak are literally translated as "father". Bapak is more formal and is used much like the English word, "sir". Saudara (for men) or Saudari (for women) is another term of greater respect and formality. It translates to "kinsman", "lady", or "gentleman". Ibu is literally translated as "mother". It is used as "ma'am" or "lady" would be in English. If addressing a man whose name is unknown, one uses Bapak and if addressing a woman whose name is unknown, one uses Ibu. An informal way to address a significantly older person is to use Om, Paman, Bibi, or Tante, which mean "uncle" and "aunt". The terms are Dutch-influenced and quite commonly used in the big cities. Local honorifics continue to be employed throughout Indonesia. In a casual situation, Kakak is used to address a person as an older sister or brother. In Javanese Mbak is used for "older sister" and Mas is used for "older brother". Mbak and Mas are used for example to address junior staff in cafes and restaurants in Jakarta. In Sumatran Malay or Minangkabau cultural spheres, an older brother is addressed as Abang. However, it is also common to address a becak driver, angkot driver, vegetable vendor, fishmonger, or hawker with Abang. "Gus" (from bagus) is used exclusively to address an honorable Eastern Javanese person with a strong traditional and religious identity. For example, the Indonesian former president, Abdurrahman Wahid, was often addressed as Gus Dur; "Dur" being the short form of his first name, Abdurrahman. Royalty For Indonesian royalty, the titles "Sri" and "Prabhu" are used to address kings and monarchs, usually in Indianized kingdoms located in the islands of Sumatra, Java, Bali, Borneo, and other places which had Hindu/Buddhist influence. "Sri Baginda" or "Sri Paduka Baginda" is the formal title used to address a king, for example the sultan of Yogyakarta, Sri Sultan Hamengkubuwono