Cadena nacional

In several Latin American countries, a ' (; plural '), also referred to as a ' () or ' () is a joint transmission through the media, generally radio and television stations, which aims to reach the largest number of inhabitants of a State. These types of broadcasts are usually of a political nature, since they are mostly messages from government authorities about different matters of general interest, as well as the transmission of electoral debates for the elections to the executive power of each country. 
The institutional characteristics of the national chain vary according to the legislation and customs of each country.  It may be a resource officially provided for in legislation or the name may be used informally, to describe a coordinated transmission. The coupling of the different media to the signal of the official chain can also be voluntary or compulsory.  Similarly, the national network can be used for different types of transmissions in addition to the official messages of the State authorities.
Criticism.
Argentina.
During the government of Cristina Kirchner, the number and frequency of "Cadenas Nacionales" increased, some media criticized their use as not limited to cases of "institutional significance".
The then National Senator for Citizen Unity Cristina Fernández de Kirchner, at the presentation of his book "Sinceramente" in Rosario (Argentina), said that "he does not regret the national channels, since otherwise the media would not have shown the public policies of the then President of Argentina". 
During the administration of the President Mauricio Macri, its use decreased.
Chile.
In Chile, during the period of the Popular Unity, some radio stations (mainly from the opposition), got off the "Cadenas Nacionales" to broadcast their normal programming. At that time they were mandatory.
Honduras.
Another similar situation was the opposition, on the part of the Honduran press, to broadcasting national channels during the government of President Manuel Zelaya, considering that "in the past the "cadena nacional" system was used constantly, mainly by the de facto governments, without satisfactory results".
Venezuela.
Mandatory national channels with political content have been strongly criticized by some media, since in some countries they must broadcast content that often differs from their editorial line. 
That was the case of the radio station RCTV in Venezuela, an opponent of Hugo Chávez, which refused to broadcast a message from the ruler in 2007, despite the fact that in said country there is a Law on Social Responsibility in Radio and Television, which obliges radio and television to broadcast information from the Executive Power. Currently, a "Cadena nacional" is broadcast almost every day, normally headed by Nicolás Maduro or Delcy Rodríguez.