Since the May Fourth Movement, written vernacular Chinese had replaced Classical Chinese and emerged as the mainstream written Chinese in the Republic of China. But Classical Chinese continued to be widely used in the Government of the Republic of China. Most government documents in the Republic of China were written in Classical Chinese until reforms in the 1970s, in a reform movement spearheaded by President Yen Chia-kan to shift the written style to a more integrated vernacular Chinese and Classical Chinese style (文白合一行文). After January 1, 2005, the Executive Yuan also changed the long-standing official document writing habit from vertical writing style to horizontal writing style.