Соответствующая норма
Spain
Practice relating to Rule 66. Non-Hostile Contacts between the Parties to the Conflict
Spain’s LOAC Manual (1996) notes that the belligerents may conclude special oral agreements on specific questions, such as agreements to allow the search for the wounded or for the flight of a medical aircraft over a small zone controlled by the enemy. Those simple low-level arrangements may be concluded by radio or by bearer of a white flag. Higher-level agreements must be concluded in writing (e.g. the establishment of demilitarized zones, or the flight of a medical aircraft over a large zone controlled by the enemy). 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, Division de Operaciones, 18 March 1996, Vol. I, §§ 2.6.a and 10.8.f.(3).
The manual adds:
A truce is defined as a temporary interruption of military operations, limited to a specific area and usually concluded between local commanders. It shall regularly serve a humanitarian purpose, to facilitate the removal, the exchange and transport of wounded left on the battlefield, for the evacuation or exchange of wounded and sick from a besieged area, and for the passage of medical and religious personnel and medical equipment on their way to such areas.
In addition to parlementaires, the parties in conflict may communicate through the mediation of the Protecting Powers …
If the parties in conflict have not agreed upon the designation of a Protecting Power, the ICRC, or any other impartial and efficient organization, may act as a “substitute”
One of the most usual missions of the military observers taking part in peacekeeping operations is to act as intermediaries between the parties to the conflict to facilitate the negotiation and implementation of local agreements. 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, Division de Operaciones, 18 March 1996, Vol. I, §§ 2.6.b.(1) and 2.6.c.(2)-(4).
Spain’s LOAC Manual (2007) states:
2.6. AGREEMENTS WITH THE ADVERSE PARTY
The parties to the conflict can conclude special agreements on specific matters, which are normally negotiated and approved by military bodies, although the involvement of civilian or political bodies is sometimes required. Such agreements may not restrict the protection established by the law of armed conflict for people and property. … Agreements can be made on whatever matters are deemed appropriate. The law of armed conflict does not specify which matters can be the subject of agreements, but expressly provides for the ones considered most relevant.
The military personnel of countries that agree to take part in peacekeeping operations can participate as military observers, with the mission of facilitating the negotiation and observance of local agreements and investigating violations of truces and ceasefires.
2.6.a. FORM OF AGREEMENTS
The parties to a conflict can also make verbal agreements, which are normally local, short-term or emergency agreements, such as local agreements to search for and collect the wounded after armed confrontations or an agreement for the flight of a medical aircraft over a small area controlled by the enemy, etc.
Agreements should be made in writing when they are broader in scope and long term, such as agreements for hospital zones, demilitarized zones, neutralized zones, non-defended localities, the flight of medical aircraft over large areas controlled by the enemy, the evacuation of an area under siege, etc.
2.6.b. AGREEMENTS AFFECTING HOSTILITIES
2.6.b.(1). Ceasefires
A ceasefire is a temporary cessation of military operations limited to a specific area and usually agreed between local commanders. They are normally established for humanitarian reasons to facilitate the removal, exchange and transport of the wounded left on the battlefield, the removal and exchange of the wounded and sick from a besieged or encircled area or for the passage of medical and religious personnel and equipment on their way to such areas.
All duly authorized ceasefires must be observed.
2.6.c.(2). Representatives of the Protecting Powers
In addition to the use of parlementaires, the parties to the conflict can also communicate with each other through the Protecting Powers.
2.6.c.(3). Delegates of the International Committee of the Red Cross
If the parties to the conflict do not agree on the designation of a Protecting Power, the ICRC or any other impartial and effective humanitarian organization can act in its place as a “substitute”. 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, §§ 2.6, 2.6.a, 2.6.b, 2.6.b.(1), 2.6.c.(2) and 2.6.c.(3).
The manual further states:
Commanders of opposing forces may establish agreements at any time, provided that they do not adversely affect the status of persons protected under international law. They can use whatever means they have at their disposal to this end. 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 7.5.b.
The manual also states:
The representatives or delegates of the Protecting Power(s) and delegates of the ICRC or any other international humanitarian organization are entitled to the same status as parlementaires and the personnel of neutral States. 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 5.2.a.(3).(b); see also § 7.5.c.
Spain’s LOAC Manual (2007) states: “The white flag is the distinctive sign of parlementaires.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 5.2.d.(1).
The manual also states: “The usual and generally accepted way of expressing an intention to negotiate is to wave a white flag.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 7.5.c.
Spain’s Field Regulations (1882) provides that a parlementaire is “the official sent to the enemy with formal orders and powers to negotiate agreements, capitulations; to request suspension of arms, truce or armistice; to present claims or observations about violations of agreements”. 
Spain, El Reglamento para el Servicio de Campaña, 4 January 1882, § 901.
Spain’s LOAC Manual (1996) defines parlementaires as “the persons authorized by one of the parties to enter into negotiations with the adversary, and who advances bearing a white flag”. 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, Division de Operaciones, 18 March 1996, Vol. I, § 2.6.c.(1).
Spain’s LOAC Manual (2007) states: “Parlementaires are those who have been authorized by one of the parties to the conflict to enter into communication with the other, bearing a white flag.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 2.6.c.(1); see also §§ 5.2.a.(1).(b) and 7.5.c.
Spain’s Field Regulations (1882) states that a commander may refuse to receive a parlementaire only if it would result in an immediate and manifest prejudice to operations or if it appears to be a dilatory manoeuvre. 
Spain, El Reglamento para el Servicio de Campaña, 4 January 1882, § 903.
Spain’s LOAC Manual (1996) provides: “The commander to whom a parlementaire is sent is not obliged to receive him in every case.”  
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, Division de Operaciones, 18 March 1996, Vol. I, § 2.6.c.(1).
Spain’s LOAC Manual (2007) states: “Commanders to whom parlementaires are sent are not obliged to receive them.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 2.6.c.(1); see also § 7.5.c.