Free programs are available offering this Unicode extension, which allow users to type Russian characters, even on Western 'QWERTY' keyboards. Computing The Russian alphabet has many systems of character encoding. KOI8-R was designed by the Soviet government and was intended to serve as the standard encoding. This encoding was and still is widely used in UNIX-like operating systems. Nevertheless, the spread of MS-DOS and OS/2 (IBM866), traditional Macintosh (ISO/IEC 8859-5) and Microsoft Windows (CP1251) meant the proliferation of many different encodings as de facto standards, with Windows-1251 becoming a de facto standard in Russian Internet and e-mail communication during the period of roughly 1995–2005. All the obsolete 8-bit encodings are rarely used in the communication protocols and text-exchange data formats, having been mostly replaced with UTF-8. A number of encoding conversion applications were developed. "iconv" is an example that is supported by most versions of Linux, Macintosh and some other operating systems; but converters are rarely needed unless accessing texts created more than a few years ago. In addition to the modern Russian alphabet, Unicode (and thus UTF-8) encodes the Early Cyrillic alphabet (which is very similar to the Greek alphabet), and all other Slavic and non-Slavic but Cyrillic-based alphabets. Orthography The current spelling follows the major reform of 1918, and the final codification of 1956. An update proposed in the late 1990s has met a hostile reception, and has not been formally adopted. The punctuation, originally based on Byzantine Greek, was in the 17th and 18th centuries reformulated on the French and German models. According to the Institute of Russian Language of the Russian Academy of Sciences, an optional acute accent () may, and sometimes should, be used to mark stress. For example, it is used to distinguish between otherwise identical words, especially when context does not make it obvious: (zamók – "lock") – (zámok – "castle"), (stóyashchy – "worthwhile") – (stoyáshchy – "standing"), (chudnó – "this is odd") – (chúdno – "this is marvellous"), (molodéts – "well done!") – (mólodets – "fine young man"), (uznáyu – "I shall learn it") – (uznayú – "I recognize it"), (otrezát – "to be cutting") – (otrézat – "to have cut"); to indicate the proper pronunciation of uncommon words, especially personal and family names, like (aféra, "scandal, affair"), (gúru, "guru"), (García), (Olésha), (Fermi), and to show which is the stressed word in a sentence, for example (Tý syel pechenye? – "Was it