Mathematical Sans-serif Bold Italic Small S (U+1D668) is a Unicode lowercase letter from the Mathematical Alphanumeric Symbols block. It resides on Plane 1 (SMP, Supplementary 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 𝙨 or 𝙨. Because it is outside the Basic Multilingual Plane, proper font support is required; otherwise a fallback box may be shown.