The right-to-left mark (RLM) is a
non-printing character used in the computerized
typesetting
Typesetting is the composition of text by means of arranging physical ''type'' (or ''sort'') in mechanical systems or '' glyphs'' in digital systems representing '' characters'' (letters and other symbols).Dictionary.com Unabridged. Random ...
of
bi-directional text
A bidirectional text contains two text directionalities, right-to-left (RTL) and left-to-right (LTR). It generally involves text containing different types of alphabets, but may also refer to boustrophedon, which is changing text direction in ...
containing a mix of left-to-right scripts (such as
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
and
Cyrillic) and right-to-left scripts (such as
Arabic
Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walte ...
,
Syriac Syriac may refer to:
* Syriac language, an ancient dialect of Middle Aramaic
*Sureth, one of the modern dialects of Syriac spoken in the Nineveh Plains region
* Syriac alphabet
** Syriac (Unicode block)
** Syriac Supplement
* Neo-Aramaic languages ...
, and
Hebrew
Hebrew (; ; ) is a Northwest Semitic language of the Afroasiatic language family. Historically, it is one of the spoken languages of the Israelites and their longest-surviving descendants, the Jews and Samaritans. It was largely preserved ...
).
RLM is used to change the way adjacent characters are grouped with respect to text direction. However, for
Arabic script,
Arabic letter mark may be a better choice.
Unicode
In
Unicode
Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, ...
, the RLM character is encoded at .
In
UTF-8
UTF-8 is a variable-length character encoding used for electronic communication. Defined by the Unicode Standard, the name is derived from ''Unicode'' (or ''Universal Coded Character Set'') ''Transformation Format 8-bit''.
UTF-8 is capable of ...
it is
E2 80 8F. Usage is prescribed in the Unicode Bidi (bidirectional) Algorithm.
[UNICODE 12.0 Standard, http://www.unicode.org/versions/Unicode12.0.0/UnicodeStandard-12.0.pdf, p. 880]
Example of use in HTML
Suppose the writer wishes to inject a run of Arabic or Hebrew (i.e. right-to-left) text into an English paragraph, with an exclamation point at the end of the run on the left hand side. "I enjoyed staying -- really! -- at his house." With the "really!" in Hebrew, the sentence renders as follows:
I enjoyed staying -- באמת
! -- at his house.
(Note that in a computer's memory, the order of the Hebrew characters is ב,א,מ,ת.)
With an RLM added after the exclamation mark, it renders as follows:
I enjoyed staying -- באמת
! -- at his house.
(Standards-compliant browsers will render the exclamation mark on the right in the first example, and on the left in the second.)
This happens because the browser recognizes that the paragraph is in a LTR script (
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
), and applies punctuation, which is neutral as to its direction, in coordination with the surrounding (left-to-right) text. The RLM causes the punctuation to be surrounded by only RTL text—the Hebrew and the RLM—and hence be positioned as if it were in right-to-left text, i.e., to the left of the preceding text.
See also
*
Arabic letter mark
*
Left-to-right mark
*
Bidirectional text
A bidirectional text contains two text directionalities, right-to-left (RTL) and left-to-right (LTR). It generally involves text containing different types of alphabets, but may also refer to boustrophedon, which is changing text direction in ...
References
External links
Unicode standard annex #9: The bidirectional algorithm
*Unicode
Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, ...
Control characters
Digital typography
Unicode formatting code points
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