 bi-directional text is text containing text in both text directionalities, both right-to-left (rtl or dextrosinistral) and left-to-right (ltr or sinistrodextral). it generally involves text containing different types of alphabets, but may also refer to boustrophedon, which is changing text directionality in each row. some writing systems of the world, notably the arabic and hebrew scripts, and derived systems such as the urdu, persian, kurdish and yiddish scripts, are written in a form known as right-to-left (rtl), in which writing begins at the right-hand side of a page and concludes at the left-hand side. this is different from the left-to-right (ltr) direction used by most languages in the world. when ltr text is mixed with rtl in the same paragraph, each type of text is written in its own direction, which is known as bi-directional text. this can get rather complex when multiple levels of quotation are used. many computer programs fail to display bi-directional text correctly. for example, the hebrew name sarah (×©×¨×) is spelled sin (×©) resh (×¨) heh (×) from right to left. note: some web browsers may display the hebrew text in this article in the opposite direction. == unicode support == bidirectional script support is the capability of a computer system to correctly display bi-directional text. the term is often shortened to bidi or bidi. early computer installations were designed only to support a single writing system, typically for left-to-right scripts based on the latin alphabet only. adding new character sets and character encodings enabled a number of other left-to-right scripts to be supported, but did not easily support right-to-left scripts such as arabic or hebrew, and mixing the two was not practical. right-to-left scripts were introduced through encodings like iso/iec 8859-6 and iso/iec 8859-8, storing the letters (usually) in writing and reading order. it is possible to simply flip the left-to-right display order to a right-to-left display order, but doing this sacrifices the ability to correctly display left-to-right scripts. with bidirectional script support, it is possible to mix scripts from different scripts on the same page, regardless of writing direction. in particular, the unicode standard provides foundations for complete bidi support, with detailed rules as to how mixtures of left-to-right and right-to-left scripts are to be encoded and displayed. in unicode encoding, all non-punctuation characters are stored in writing order. this means that the writing direction of characters is stored within the characters. if this is the case, the character is called "strong&qu
Character_encoding Internationalization_and_localization Unicode_algorithms