The Google search engine published the most popular searches of Ukrainians in 2018. The word "tomos" was in third place in the query "what is this?"
Tomos is a document issued by the Orthodox Church of Constantinople (the governing center of the church is geographically located in Istanbul). It so traditionally happened that today it is the first among equals, and, according to the decisions of the Ecumenical Councils, this church is assigned the function of a kind of arbiter in inter-Orthodox relations.
Tomos confirms the right of a certain Orthodox Church to have full autocephaly (i.e. self-government). It cannot be influenced by other churches, with the exception of the "right of appeal" (Constantinople can consider appeals of the priests of this church).
Autocephaly is the independent state of the church. According to the canons, there are several such states: exarchate (part of another church, for example, the Ukrainian exarchate of the Russian Orthodox Church); an autonomous church, but it is still associated with another, larger church; and autocephaly status is an independent church.
The status of this independence is just spelled out in the tomos. This is a document that is issued at the beginning of the creation of the church, it means giving it a certain status: autonomy and autocephaly. The tomos governs various points regarding the independent state of the church. For example, its name, the name of the primate, who controls it, and other details.
