The terms are: third-country national, written confirmation, diplomatic note holders unable to secure a test, EU Member States
The Ministry of Health of the Czech Republic stipulates:
According to point III/10 (only in Czech), a citizen of a third country is a foreigner except for a citizen of the European Union and a foreigner within the meaning of Section 1(3) of Act No. 326/1999 Coll., on the Residence of Foreigners in the Territory of the Czech Republic and on Amendments to Certain Acts, as amended,
According to point III/11 (only in Czech), for the purposes of this protection measure, in addition to the Member States of the European Union, the Principality of Andorra, the Republic of Iceland, the Principality of Liechtenstein, the Principality of Monaco, the Kingdom of Norway, the Republic of San Marino, the Swiss Confederation and the Vatican City State are also considered to be the Member States of the European Union,
According to point III/12 (only in Czech), for the purposes of this safeguard measure, the term "written confirmation" means both in paper form (original or plain copy) and in electronic form, provided that it includes the name, surname, and date of birth or travel document number of the specific addressee; written confirmation in electronic form cannot be submitted in the form of SMS messages,
According to point III/13 (only in Czech), the holders of the diplomatic note on the impossibility of securing a SARS-CoV-2 virus test in the country of departure may be citizens of the Czech Republic and their family members traveling together as referred to in point II.2 e) with a temporary residence permit issued by the Czech Republic, citizens of the European Union with a temporary residence permit issued by the Czech Republic, foreigners with a permanent residence permit issued by the Czech Republic and foreigners referred to in point II.3 d) or I.10. h).
The full wording of the measure can be found here (only in Czech).