7. Where contracting states opt to grant nationality upon application, it is permissible for them to do so subject to the fulfilment of certain conditions. Permissible conditions are listed exhaustively in Article 1(2) of the 1961 Convention and include: a fixed period for lodging an application immediately following the age of majority (Article 1(2)(a)); habitual residence in the contracting state for a fixed period, not to exceed five years immediately preceding an application nor ten years in all (Article 1(2)(b)); restrictions on criminal history (Article 1(2)(c)); and the condition that an individual has always been stateless (Article 1(2)(d)). Providing for a discretionary naturalisation procedure for otherwise 8. stateless children is not permissible under the 1961 Convention. A state may choose not to apply any of the permitted conditions and simply grant nationality upon submission of an application. Contracting states that opt to grant nationality upon application pursu9. ant to Article 1(1)(b) of the 1961 Convention, should accept such applications from children who would otherwise be born stateless in their territory as soon as possible after their birth and during childhood. However, where contracting states set deadlines to receive applications from otherwise stateless individuals born in their territory at a later time, they must accept applications lodged at a time beginning not later than the age of 18 and ending not earlier than the age of 21 in accordance with Article 1(2)(a) of the 1961 Convention. These provisions ensure that otherwise stateless individuals born in the territory of a contracting state have a window of at least three years after majority to lodge their application. 10. The condition of a period of “habitual residence” on the territory of the country of birth in order to acquire that country’s nationality is not to exceed five years immediately preceding an application nor ten years in total. “Habitual residence” should be understood as stable, factual residence and does not imply a legal or formal qualification. The 1961 Convention does not allow contracting states to make an application for the acquisition of nationality of otherwise stateless individuals conditional on a lawful residence.7 In this respect, the 1961 Convention differs from Article 6(2) of the Council of Europe European Convention on Nationality (hereafter, ECN) (ETS No. 166), which provides that children born on the territory of a state party who do not acquire another nationality at birth should acquire the nationality of the country of 7. See UNHCR Guidelines on statelessness No. 4 – Ensuring Every Child’s Right to Acquire a Nationality through Articles 1-4 of the 1961 Convention on the Reductions of Statelessness (hereafter, UNHCR Guidelines on statelessness No. 4), paras. 40-43. Page 8 ►Stateless children’s access to nationality