Claim: The logo of HRT 1 (operated neither by a Croatian nor a Slovenian public broadcasting company) from 1956 to 1970 has stylized white circles in square making "RTZ"; which evolved in to a yellow RTZ with small captions from 1972 to June 1990.
Evidence: HRT 1 (HTV 1, "Prvi program") is the Croatian public television channel, operated by Hrvatska Radiotelevizija.