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Drafting Section on Numbers
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ntounsi committed Jun 25, 2017
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Expand Up @@ -1531,7 +1531,138 @@ <h3><a href="#h_mixedscript">Considerations for mixed-script text</a>
<h3><a href="#h_numbers">Arabic numbering</a>
</h3>


<section id="h_Arabic_number_writing">
<h4><a href="#h_Arabic_number_writing">Arabic number writing</a> </h4>
<p>There are mostly two families of <span style="font-family: Waseem;">numerals</span>
in Arabic script. One known as European digits aka as Arabic Digits
(Unicode range U+0030-U+0039), the second is Arabic-Indic Digits
(Unicode range U+0660-U+0669). The latter further gave another
sub-notation for Persian/Urdu digits, the Extended (or Eastern)
Arabic-Indic Digits (Unicode range U+06F0-U+06F9), in which digits
4, 5 and 6 have another glyph. The following table summarizes those
families:</p>
<figure id="order_in_memory"> <img style="width: 465px; height: 95px;"
src="images/Arabic-numeral.png"
alt="Arabic Numerals">
<figcaption> Different notations for Arabic script digits </figcaption>
</figure>
<p>Digits on the first row are predominant in Western Arabic regions,
while the second row digits are used in most of the Middle-East
countries, sometime along with the former. Persian and Urdu mostly
use the third category.</p>
<p>Arabic numbers are written with the lowest significant digits to
the right and the highest digits to the left. That arrangement is
identical to the Western one, even though Arabic script is written
from right to left. Numbers with many digits use delimiters for the
decimal part and thousands separator :</p>
<p>Western digits use comma (U+002C) and full stop (U+002E)
indifferently as decimal and thousands separator: </p>
<ul>
<li>1.234,5 in Western (francophone) regions.</li>
<li>1,234.5 in Middle-East (anglophone) regions.</li>
<li>Thin space (U+2009) or narrow no-break space (U+202F) may also
be used as thousands separator.</li>
</ul>
<p>Arabic-Indic numerals use two specific separators:</p>
<ul>
<li>Arabic Decimal Separator ٫ (U+066B) like comma.</li>
<li>Arabic Thousand Separator ٬ (U+066C).</li>
<li>Example : ١٬٢٣٤٫٥&nbsp;.</li>
</ul>
<p>An important fact to note here is the bidirectional category of
these numbers.</p>
<ul>
<li>European Digits (U+0030 - U+0039) are of category "EN - European
number",</li>
<li>Arabic-Indic Digits (U+0660 - U+0669) are "AN - Arabic number",</li>
<li>Eastern Arabic-Indic Digits (U+06F0 - U+06F9) are classified "EN
- European number", differently from their counterpart just above.</li>
</ul>
<p>The difference in Bidi category between Arabic-Indic digits and
Eastern Arabic-Indic digits is due to the difference in Bidi
behavior desired in Arabic <i>vs</i>. Persian. </p>
<p class="issue"> What is the origin of this decision.</p>
<p>As a consequence, a sentence like « Five is written ۵ in Iran and ٥
in Egypt », say, will give (in RTL context) </p>
<p>« ‫Five is written ۵ in Iran and ٥ in Egypt‬ » </p>
<p>requiring the use of markup to correct it. Which is not the case
with the sentence « Five is written ۵ in Iran and 5 in Morocco ». </p>
</section>
<section id="h_Arabic_number_in_other_uses">
<h4><a href="#h_Arabic_number_in_other_uses">Arabic number in other
uses</a></h4>
<p>Numbers do not always appear alone, and may come with other
characters like financial symbols, fraction sign, decimals and/or
thousands signs (excluding math expressions here). At first, there
are proper signs used for the script such as Arabic percent/permille
sign ٪ (U+066A) and ؉&nbsp; (U+0609), Arabic decimal " ٫ " (U+66B)
and thousands&nbsp; " ٬ " (U+066C) separators, mentioned earlier and
mostly used with Arabic-Indics. </p>
<p>Numerals can also come separated by or mixed with space or other
signs. Example are phone numbers
+12&nbsp;34&nbsp;56&nbsp;78&nbsp;89, cars licence plate like
123&nbsp;د‎&nbsp;4,&nbsp; quantities 37.5°, &nbsp; ٥٠ كلم (50km)
etc. </p>
<p>A particular attention is needed here. Firstly, numbers have a weak
directionality with regards to Bidi algorithm. For example,
alongside a number, certain otherwise neutral characters, such as
negative/positive sign, currency or degree symbols, are likely to be
treated as part of the number rather than a neutral.</p>
<p>Secondly, the placement of the accompanying signs and symbols may
depend on regions. Generally Middle East (or anglophone regions) vs.
Western (or francophone regions). This is not to mention punctuation
signs.</p>
<ul>
<li> The percent sign is to be placed on the left after the number
(٪١٢ not ١٢٪), without space (٪&nbsp;١٢). With European numbers,
the % percent sign is sometime used, and placed indifferently on
the right or the left of the digits (12% or %12).</li>
<li>Arabic decimal and thousand sign obey to the same rule as for
European numbers (١٬٢٣٤٫٥٦). European signs are used with
European numbers (1.234,56 or 1,234.56).</li>
<li>Money or currency signs when they come alongside a number, are
to be placed at the left and be treated as part of the number
rather than a neutral (€12.3 or €١٢٫٣).</li>
<li>Unlike degree sign that is to be placed at the right of the
number (37.5°&nbsp;C, ٩٩٫٥°&nbsp;F) or (<span dir="rtl">37.5°&nbsp;م</span>,
<span dir="rtl">۹۹٫۵°&nbsp;ف</span>).</li>
<li>For quantities measurement, there should a
separating space (<span dir="rtl">12&nbsp;كغ</span>, <span dir="rtl">٤٥&nbsp;مم</span>).
</li>
<li>The same apply when using range of values. (<span dir="rtl">12-15&nbsp;كغ</span>,
but <span dir="rtl">12٪-15٪&nbsp;كغ</span>).</li>
<li> Solidus sign " / " (U+002F) is used for fraction or ratio
notation. Fraction are noted for one-half, say, 2/1 or ٢/١, mostly
in RTL mode. There is no standard way, however, and some
region/author may write 1/2 for European digits. </li>
<p class="issue">May be use image for examples.</p>
<li>Notation with Solidus sign " / " are used in:<br>
<ul>
<li>Notation such as speed "50 km/h"<br>
كم/س ‎ 50</li>
<li>Notation such as "Page / Volume", for example a reference to
a page in a volume<br>
١٢٣/١ for volume ١, page ١٢٣</li>
<li>or reference to Quran "Verse / Surah",<br>
١٣/٩٠ for Surah 90, Verse 13</li>
<li>Mark or rank in a classification <br>
20/15 for rank 15 over 20</li>
<li>Dates (2017/06/24, ٢٠١٧/٠٦/٢٤)</li>
<p class="issue">Look for evidence for some examples</p>
</ul>
</li>
</ul>
<p>Other issues</p>
<p class="issue"> How to know that a sign (space, comma ...) is a separator or a
sign within a number? <code>+12&nbsp;34&nbsp;56&nbsp;78&nbsp;90</code>
is a phone number or a sequence of digits? Which may be inverted
in RTL. A tip is to use a syntax like <code>12.34.56.78.90</code>
or <code>12-34-56-78-90</code> for phones.</p>
<p class="issue">May be mention the Decimal Separator Key Symbol " ⎖ " (U+2396),
used with keyboards (resembles an apostrophe)</p>
</ul>
</section>
<p><b><i>Old text bellow</i></b></p>
<p>Arabic script uses non-European digits for numbers in certain locales and situations.</p>


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