U+FE7D ARABIC SHADDA MEDIAL FORM

U+FE7D was added to Unicode in version 1.1 (1993). It belongs to the block Arabic Presentation Forms-B in the Basic Multilingual Plane.

This character is a Other Letter and is mainly used in the Arabic script.

The glyph is a Medial composition of the glyphs . It has a Neutral East Asian Width. In bidirectional context it acts as Arabic Letter and is not mirrored. In text U+FE7D behaves as Alphabetic regarding line breaks. It has type OLetter for sentence and ALetter for word breaks. The Grapheme Cluster Break is Any.

The Wikipedia has the following information about this codepoint:

Shaddah (Arabic: شَدَّة‎ shaddah "[sign of] emphasis", also called by the verbal noun from the same root, tashdid تشديد tashdīd "emphasis"), is one of the diacritics used with the Arabic alphabet, marking a long consonant (geminate). It is functionally equivalent to writing a consonant twice in the orthographies of languages like Latin, Italian, Swedish, and Ancient Greek, and is thus rendered in Latin script in most schemes of Arabic transliteration, e.g. رُمَّان = rummān 'pomegranates'.

In shape, it is a small letter س s(h)in, standing for shaddah. It was devised for poetry by al-Khalil ibn Ahmad in the eighth century, replacing an earlier dot.

When a shadda is used on a consonant which also takes a fatḥah /a/, it is written above the shaddah, while if it had a kasrah (a dash below the consonant indicating that it takes a short /i/ as its vowel), the kasrah is written between the consonant and the shaddah, under the shaddah, rather than in its normal place.

Consonant length in Arabic is contrastive: دَرَسَ darasa means 'he studied' while دَرَّسَ darrasa means 'he taught'; بَكى صَبِي bakā ṣabī means 'a youth cried' while بَكّى الصَّبِي bakkā ṣ-ṣabī means 'a youth was made to cry'. A consonant may be long because of the form of the noun or verb; e.g., the causative form of the verb requires the 2nd consonant of the root to be long, as in darrasa above, or by assimilation of consonants, for example the l- of the Arabic definite article al- assimilates to all dental consonants, e.g. (الصّبي) (a)ṣ-ṣabī instead of (a)l-ṣabī, or through metathesis, the switching of sounds, for example أَقَلّ aqall 'less, fewer' (instead of *أَقْلَل aqlal), as compared to أَكْبَر akbar 'greater'.

A syllable closed by a long consonant is made a long syllable. This affects both stress and prosody. Stress falls on the first long syllable from the end of the word, hence أَقَلّ aqáll (or, with iʻrāb: aqállu) as opposed to أَكْبَر ákbaru, مَحَبَّة maḥábbah 'love, agape' as opposed to مَعْرِفَة maʻrifah '(experiential) knowledge'. In Arabic verse, when scanning the meter, a syllable closed by a long consonant is counted as long, just like any other syllable closed by a consonant or a syllable ending in a long vowel: أَلا تَمْدَحَنَّ a-lā tamdaḥanna 'Will you not indeed praise...?' is scanned as a-lā tam-da-ḥan-na: short, long, long, short, long, short.