Mark U+070F and U+A8FA as zero width

[Jules-Bertholet]

Unicode:

U+070F SYRIAC ABBREVIATION MARK (SAM) is a zero-width formatting code that has no effect on the shaping process of Syriac characters. The SAM specifies the beginning point of a Syriac abbreviation, which is a line drawn horizontally above one or more characters, at the end of a word or of a group of characters followed by a character other than a Syriac letter or diacritical mark.

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From Unicode, it seems that the following Arabic Prepended_Concatenation_Marks are also non-advancing:

• U+0605 NUMBER MARK ABOVE
• U+070F SYRIAC ABBREVIATION MARK
• U+0890 POUND MARK ABOVE
• U+0891 PIASTRE MARK ABOVE
• U+08E2 DISPUTED END OF AYAH

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Unicode:

U+A8FA DEVANAGARI CARET, a zero-width spacing character, marks the insertion point of omitted text, and is placed at the insertion point between two orthographic syllables. It can also be used to indicate word division