Russian orthography () is formally considered to encompass spelling () and punctuation (). Russian spelling, which is mostly phonemic in practice, is a mix of morphological and phonetic principles, with a few etymological or historic forms, and occasional grammatical differentiation. The punctuation, originally based on Byzantine Greek, was in the seventeenth and eighteenth centuries reformulated on the French and German models. The IPA transcription attempts to reflect vowel reduction when not under stress. The sounds that are presented are those of the standard language; other dialects may have noticeably different pronunciations for the vowels. Spelling Russian is written with a modern variant of the Cyrillic script. Russian spelling typically avoids arbitrary digraphs. Except for the use of hard and soft signs, which have no phonetic value in isolation but can follow a consonant letter, no phoneme is ever represented with more than one letter. Morphological principle Under the morphological principle, the morphemes (roots, suffixes, infixes, and inflexional endings) are attached without modification; the compounds may be further agglutinated. For example, the long adjective шарикоподшипниковый, sharikopodshipnikoviy ('pertaining to ball bearings'), may be decomposed as follows (words having independent existence in boldface): Note again that each component in the final production retains its basic form, despite the vowel reduction. The phonetic assimilation of consonant clusters also does not usually violate the morphological principle of the spelling. For example, the decomposition of счастье ('happiness, good fortune') is as follows: Note the assimilation with - so that it represents the same sound (or cluster) as -. The spelling <щастие> was fairly common among the literati in the eighteenth century, but is usually frowned upon today. Phonetic principle The phonetic principle implies that: all morphemes are written as they are pronounced in isolation, without vowel reduction, Church Slavonic style, or, more strictly, taking inflexion into account (this in combination with the morphological agglutination described above is sometimes called the morphemic principle); certain prefixes that end in a voiced consonant (in practice, only those in - ) have that consonant devoiced (become ) to voicing assimilation. This may be reflected orthographically. For example, for the prefix/preposition без 'without': certain roots and prefixes occasionally have their vowel modified in individual cases to reflect historical changes in pronunciation, usually as a result of being unstressed or, conversely, stressed. In practice, this usually applies to -- changing to -- or (akanye), and alternations between the allophonic vowels and (represented