sino-vietnamese characters were eventually displaced by an alphabetic script. unlike alphabets used elsewhere, the vietnamese alphabet has marks to indicate tone. in contrast to south korea and japan, modern vietnam does not require students to study the traditional characters. fewer than 100 scholars worldwide can read nôm. vietnamese literature written in nôm, including classics like "tale of kieu" and the poetry of ho xuan huong, can now be read only in translation. however, character calligraphy remains popular as a home decoration and as a symbol of good luck. the han-nom institute, founded in 1970, collects and studies relevant manuscripts. the nôm ideographs were added to unicode in 2001. unicode is an international electronic encoding standard.