. Identification re ention and reduction o state essness worldwide have a clear international legal obligation to grant nationality to children that would otherwise be stateless. In addition, the 57 OSCE participating States can draw upon their politically binding commitments and principles. Birth registration can be fundamental in acquiring a nationality because: — Birth registration provides official documentation of where a person was born (relevant where nationality is acquired by jus soli, i.e. birth on the territory); and — Birth registration provides official documentation of who a person’s parents are (essential for acquisition of nationality by jus sanguinis, i.e. based on descent). The following categories of persons, which are not mutually exclusive, may be at particular risk of statelessness owing to the absence of or incomplete birth registration: — persons living in border areas where the lack of birth registration may lead to confusion as to whether they are nationals of one State or another; — minorities and persons who have perceived or actual ties with other States; — nomadic or semi-nomadic populations whose territories cross international borders; — children of refugees and asylum-seekers born abroad; — migrant populations in which difficulties to prove nationality of the country of origin may occur when one or more generations of children are born abroad (a risk that increases with each successive generation); — children born to undocumented parents. The risk of statelessness for such groups may increase as a result of other circumstances. For example, in some cases girls are not registered because the family is not able or willing to take the necessary administrative action for them; or because children are born out of wedlock, particularly 53