The Arabic letter mark (ALM) is a non-printing character used in the computerized typesetting of bi-directional text containing mixed left-to-right scripts (such as Latin and Cyrillic) and right-to-left scripts (such as Persian, Arabic, Syriac and Hebrew).

Similar to the right-to-left mark (RLM), it is used to change the way adjacent characters are grouped with respect to text direction, with some difference on how it affects the bidirectional level resolutions for nearby characters.

Unicode

In Unicode, the ALM character is encoded at U+061C ؜ ARABIC LETTER MARK. In UTF-8 it is 0xD8 0x9C. Usage is prescribed in the Unicode Bidirectional Algorithm.