Cjk Compatibility Ideograph-f91b (U+F91B) is a Unicode other letter from the CJK Compatibility Ideographs block. It resides on Plane 0 (BMP, Basic Multilingual Plane), has bidirectional class L (left-to-right), is not mirrored, and has combining class 0 (Not Reordered). In HTML it can be written as 亂 or 亂.