even 'Indian Indians'. Foreign Indians may be distinguished in terms of residency status. Well educated professionals or entrepreneurs with a high earning capacity are granted renewable Employment Passes. These entitle the holder's spouse, children and parents to Dependents Passes. Students may enter on Students Passes. Pass holders may apply for Permanent Residence, which lets them live in Singapore on a long term-basis. As part of Singaporean nationality law, they are also eligible to apply for Singapore Citizenship. In contrast, unskilled foreign workers enter Singapore with Work Permits. They are rarely allowed to stay in Singapore for more than two years and are never allowed to bring dependents with them. Nor are they eligible to apply for either Permanent Residence or Citizenship. Demographic statistics are generally restricted to 'Singapore residents', defined as both Singapore citizens and Permanent Residents. Many of the statistics about Indians in Singapore in this article are restricted to this group. Scholars have noted "(o)fficial figures for workers on temporary contracts are difficult to obtain because the Ministry of Manpower in Singapore considers the information sensitive." Consequently, there is limited information about short-term or 'non-resident' Indians in Singapore. Note that use of the term 'non-resident' Indian should not be confused with the concept of the Non Resident Indian or NRI, which the government of the Republic of India uses to describe its citizens living abroad. In Singapore, an NRI may be statistically non-resident (in the case of work permit or pass holders) or he/she may be considered a Singapore resident (in the case of permanent residents). Ethno-linguistic profile of Indian Singaporeans Indian Singaporean are grouped according to their respective ethnolinguistic backgrounds in the Indian subcontinent or 'dialect group'. Most Indians in Singapore have ancestral links to Southern India and Sri Lanka, with substantial groups from Northern India and Western India accounting for most of the remainder. These are generally the descendants of both free and indentured settlers from India during the 19th and early half of the 20th century. In 2010, the Singapore census categorised 237,473 Singaporeans and 110,646 permanent residents into a number of 'dialect' groups. However, these groups included Sikhs, who are a religious rather than linguistic group. Virtually all of the Sikhs are Punjabi, which was also captured as a separate 'dialect' category (comprising mainly Hindu Punjabis). Given their small absolute and relative numbers, the following table adapts the 2010 census data by combining the