Related Rule
Germany
Practice Relating to Rule 123. Recording and Notification of Personal Details of Persons Deprived of Their Liberty
Germany’s Military Manual (1992) provides:
The Detaining Power is obliged to forward information regarding the fate of prisoners of war … For this purpose each of the Parties to the conflict shall institute a National Information Bureau upon the outbreak of a conflict and in all cases of occupation. The Bureau shall cooperate with the Central Tracing Agency of the ICRC. 
Germany, Humanitarian Law in Armed Conflicts – Manual, DSK VV207320067, edited by The Federal Ministry of Defence of the Federal Republic of Germany, VR II 3, August 1992, English translation of ZDv 15/2, Humanitäres Völkerrecht in bewaffneten KonfliktenHandbuch, August 1992, § 708.
Germany’s Soldiers’ Manual (2006) states:
Immediately upon their capture, or not more than one week after their arrival at a camp, prisoners of war shall be enabled to inform, in writing, their families and the Central Prisoners of War Information Agency at the International Committee of the Red Cross (19, avenue de la Paix, CH-1202 Geneva) of their capture.
When questioned, prisoners of war are bound to give only their name, first name, rank, date of birth and personal identification number. 
Germany, Druckschrift Einsatz Nr. 03, Humanitäres Völkerrecht in bewaffneten Konflikten – Grundsätze, Erarbeitet nach ZDv 15/2, Humanitäres Völkerrecht in bewaffneten Konflikten – Handbuch, DSK SF009320187, Bundesministerium der Verteidigung, R II 3, August 2006, p. 7.
In 2006, in a report in response to a request by the Parliamentary Control Panel (parliamentary body controlling intelligence services) regarding incidents relating to the Iraq war and the fight against international terrorism, Germany’s Federal Government stated:
2. Capture and transport of detainees by foreign authorities outside a formal legal procedure; reports of secret prisons and torture
abb) Assessment of the allegations under international law by the Federal Government
All measures taken to fight international terrorism must be in accordance with international law. Resolution 1566 (2004), unanimously adopted in the UN Security Council on 8 October 2004, in this context reminds States:
“that they must ensure that any measures taken to combat terrorism comply with all their obligations under international law, and should adopt such measures in accordance with international law, in particular international human rights, refugee, and humanitarian law” (preambular paragraph 6).
The obligation to adhere to international law also applies when States, fighting off a terrorist attack, an ongoing terrorist attack or an imminent attack, in a legally permissible manner invoke the right to self-defence according to Article 51 of the UN Charter.
If the right to self-defence is exercised in the context of an armed conflict, the rules of international humanitarian law, in particular the law of the 1949 Geneva Red Cross Conventions as well as the minimum human rights standards are to be respected. When fighting international terrorism outside an armed conflict, the rules of peacetime international law, in particular those on the protection of human rights, apply. This can lead to differing international law bases for capture, detention and the treatment of detainees.
With regard to the five following thematic issues, the details of the position of the Federal Government under international law are:
Prohibition on secret prisons
According to the conviction of the Federal Government, international law prohibits the installation of so-called “secret prisons”. It imperatively provides for the information of relatives or of the home State of an arrested or captured person.
“Secret or unacknowledged detention” of persons can fulfil the criteria of the prohibition of “enforced disappearances” of persons. 
Germany, Federal Government, Report in response to request by Parliamentary Control Panel (2006), 23 February 2006, pp. 55, 69–70 and 75.