competent authorizes of the Chinese Government. The term of valid ity of identification papers or residence certificates shall be determined according to the purposes of entry. Aliens residing in China shall submit their certificates to the local public security organs for examination within the prescribed period of time Article 14 Aliens who, in compliance with Chinese laws, find it necessary to establish prolonged residence in China for the purpose of investing in China or engaging in cooperative projects with Chine enterprises or institutions in the economic, scientific, technological and cultural fields, or for other purposes, are eligible for prolonged or permanent residence in China upon approval by the competent authorities of the Chinese government Article 15 Aliens who seek asylum for political reasons shall be permitted to reside in China upon approval by the competent authorities of the Chinese government Article 16 Aliens who fail to abide by Chinese laws may have their period of stay in China curtailed or their status of residence in China annulled by the competent authorities of the Chinese government Article 17 For a temporary overnight stay in China, aliens shall complete registration procedures pursuant to the relevant provisions Article 18 Aliens hold ing residence certificates who wish to change their place of residence in China must complete removal formalities pursuant to the relevant provisions Article 19 Aliens who have not acquired residence certificates or who are on a study programme in China may not seek employ ment in China without permission of the competent authorities of the Chinese Government Chapter IV Travel Article 20 Aliens who hold valid visas or residence certificates may travel to places open to aliens as designated by the Chinese government Article 21 Aliens desiring to travel to places closed to aliens must apply to local public security organs for travel permits Chapter V Exit from the Country Article 22 For exit from China, aliens shall present their valid passports or other valid certificates Article 23 Aliens belonging to any of the following categories shall not be allowed to leave China ()defendants in criminal cases or criminal suspects confirmed by a public security organ, a people's procuratorate or a people's court; (2) persons who, as notified by a people's court, shall be denied exit owing to involvement in unresolved civil cases; and ( persons who have committed other acts in violation of Chinese law who have not been dealt with and against whom the competent authorities consider it necessary to institute prosecution Article 245 competent authorizes of the Chinese Government. The term of validity of identification papers or residence certificates shall be determined according to the purposes of entry. Aliens residing in China shall submit their certificates to the local public security organs for examination within the prescribed period of time. Article 14 Aliens who, in compliance with Chinese laws, find it necessary to establish prolonged residence in China for the purpose of investing in China or engaging in cooperative projects with Chinese enterprises or institutions in the economic, scientific, technological and cultural fields, or for other purposes, are eligible for prolonged or permanent residence in China upon approval by the competent authorities of the Chinese Government. Article 15 Aliens who seek asylum for political reasons shall be permitted to reside in China upon approval by the competent authorities of the Chinese Government. Article 16 Aliens who fail to abide by Chinese laws may have their period of stay in China curtailed or their status of residence in China annulled by the competent authorities of the Chinese Government. Article 17 For a temporary overnight stay in China, aliens shall complete registration procedures pursuant to the relevant provisions. Article 18 Aliens holding residence certificates who wish to change their place of residence in China must complete removal formalities pursuant to the relevant provisions. Article 19 Aliens who have not acquired residence certificates or who are on a study programme in China may not seek employment in China without permission of the competent authorities of the Chinese Government. Chapter IV Travel Article 20 Aliens who hold valid visas or residence certificates may travel to places open to aliens as designated by the Chinese Government. Article 21 Aliens desiring to travel to places closed to aliens must apply to local public security organs for travel permits. Chapter V Exit from the Country Article 22 For exit from China, aliens shall present their valid passports or other valid certificates. Article 23 Aliens belonging to any of the following categories shall not be allowed to leave China: (1) defendants in criminal cases or criminal suspects confirmed by a public security organ, a people's procuratorate or a people's court; (2) persons who, as notified by a people's court, shall be denied exit owing to involvement in unresolved civil cases; and (3) persons who have committed other acts in violation of Chinese law who have not been dealt with and against whom the competent authorities consider it necessary to institute prosecution. Article 24