Chronicle used an era beginning with the birth of Abraham, dated in 2016 BC (AD 1 = 2017 Anno Abrahami). Spain and Portugal continued to date by the Spanish Era (also called Era of the Caesars), which began counting from 38 BC, well into the Middle Ages. In 1422, Portugal became the last Catholic country to adopt the Anno Domini system. The Era of Martyrs, which numbered years from the accession of Diocletian in 284, who launched the most severe persecution of Christians, was used by the Church of Alexandria and is still used, officially, by the Coptic Orthodox and Coptic Catholic churches. It was also used by the Ethiopian and Eritrean churches. Another system was to date from the crucifixion of Jesus, which as early as Hippolytus and Tertullian was believed to have occurred in the consulate of the Gemini (AD 29), which appears in some medieval manuscripts. CE and BCE Alternative names for the Anno Domini era include vulgaris aerae (found 1615 in Latin), "Vulgar Era" (in English, as early as 1635), "Christian Era" (in English, in 1652), "Common Era" (in English, 1708), and "Current Era". Since 1856, the alternative abbreviations CE and BCE (sometimes written C.E. and B.C.E.) are sometimes used in place of AD and BC. The "Common/Current Era" ("CE") terminology is often preferred by those who desire a term that does not explicitly make religious references but still uses the same estimated date of Christ's birth as the dividing point. For example, Cunningham and Starr (1998) write that "B.C.E./C.E. […] do not presuppose faith in Christ and hence are more appropriate for interfaith dialog than the conventional B.C./A.D." Upon its foundation, the Republic of China adopted the Minguo Era but used the Western calendar for international purposes. The translated term was (). Later, in 1949, the People's Republic of China adopted () for all purposes domestic and foreign. No year zero: start and end of a century In the AD year numbering system, whether applied to the Julian or Gregorian calendars, AD 1 is immediately preceded by 1 BC, with nothing in between them (there was no year zero). There are debates as to whether a new decade, century, or millennium begins on a year ending in zero or one. For computational reasons, astronomical year numbering and the ISO 8601 standard designate years so that AD 1 = year 1, 1 BC = year 0,