PLOS ONE Undocumented: An examination of legal identity and education provision for children in Malaysia Fig 2. Undocumented children in Malaysia according to risk of statelessness, claim to citizenship, and vulnerability to educational exclusion. https://doi.org/10.1371/journal.pone.0263404.g002 does not have the appropriate documentation to prove their legal status in the host country, restricting access to social services and movement.” Undocumented persons may have incomplete or unrecognised identity documents or no documentation at all. It is acknowledged that the term “undocumented” is often used in the context of migration, referring to undocumented or irregular migrants [33]. However, our study found that people present in Malaysia not owing to international migration may also lack the appropriate documents to prove their legal status and face implications common to undocumented migrants. We have therefore expanded the definition of being “undocumented” to apply to non-migrants in this present study. Fig 2 illustrates how undocumented children tend to be at greater risk of statelessness and educational exclusion depending on their claims to citizenship. We describe in the next section by the four categories of undocumented persons identified here: (1) Claim to Malaysian citizenship, (2) Claim to citizenship of another country, (3) Undetermined citizenship, (4) No citizenship ties with any country. (1) Claim to Malaysian citizenship. For those born in Malaysia, factors contributing to the lack of legal status in Malaysia include the legitimacy of their parents’ marriage, their mother’s nationality, and the timeliness of birth registration. Malaysian citizenship law is based on elements of the Jus Sanguinis (‘right by blood’) principle, whereby citizenship for a child is acquired through the citizenship of one or both parents. However, the situation is more complex as Malaysia does not give mothers and fathers equal rights to pass their nationality to their children [34,35]. In the specific case of Malaysian-born illegitimate children of a Malaysian father and a nonMalaysian mother (including traditional and customary marriages unrecognised by law), the child must follow the mother’s citizenship. These children are at risk of statelessness, if the non-Malaysian mother is also undocumented or untraceable. The Malaysian father cannot confer his citizenship to illegitimate children, due to the current interpretation of citizenship laws which may be called gender-discriminatory [36,37]. Logistical difficulties and prohibitive travel costs from rural or interior regions may preclude the timely registration of births at Malaysian National Registration Departments (NRD) usually located in urban areas, placing some at risk of statelessness. Two groups affected are PLOS ONE | https://doi.org/10.1371/journal.pone.0263404 February 2, 2022 6 / 26