An example is the RTL Hebrew name Sarah: שרה, spelled sin (ש) on the right, resh (ר) in the middle, and heh (ה) on the left.
Early computer installations were designed only to support a single writing system, typically for left-to-right scripts based on the Latin alphabet only.
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.
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.
Thus, in order to offer bidi support, Unicode prescribes an algorithm for how to convert the logical sequence of characters into the correct visual presentation.
Punctuation symbols that are common to many scripts, such as the colon, comma, full-stop, and the no-break-space also fall within this category.
For example, to correctly display the U+2122 ™ TRADE MARK SIGN for an English name brand (LTR) in an Arabic (RTL) passage, an LRM mark is inserted after the trademark symbol if the symbol is not followed by LTR text (e.g. "قرأ Wikipedia™ طوال اليوم.").
Unicode 6.3 recognized that directional embeddings usually have too strong an effect on their surroundings and are thus unnecessarily difficult to use.
These formatting characters were introduced after it became apparent that directional embeddings usually have too strong an effect on their surroundings and are thus unnecessarily difficult to use.
[2] Visual Studio Code highlights BiDi control characters since version 1.62 released in October 2021.
[3] Visual Studio highlights BiDi control characters since version 17.0.3 released on December 14, 2021.
[4] Egyptian hieroglyphs were written bidirectionally, where the signs that had a distinct "head" or "tail" faced the beginning of the line.
Likewise, other CJK scripts made up of the same square characters, such as the Japanese writing system and Korean writing system, can also be written in any direction, although horizontally left-to-right, top-to-bottom and vertically top-to-bottom right-to-left are the two most common forms.
Boustrophedon is a writing style found in ancient Greek inscriptions, in Old Sabaic (an Old South Arabian language) and in Hungarian runes.