2.1.1 [ISO10646] Section 19, Mirrored Characters in a Bidirectional Context
The specification states:
This character mirroring is not limited to paired characters and shall be applied to all characters belonging to that class.
All Document Modes (All Versions)
Characters for which [ISO-10646] represents the mirrored glyph as a separate code point are mirrored. For characters with no code point for the mirrored glyph, no mirroring is performed. For example, because the character 0028 LEFT PARENTHESIS has the mirrored glyph at code point 0029 RIGHT PARENTHESIS, it is mirrored.