Tibetan Vowel Sign Aa (U+0F71) is a Unicode nonspacing mark from the Tibetan block. It resides on Plane 0 (BMP, Basic Multilingual Plane), has bidirectional class NSM (nonspacing mark), is not mirrored, and has combining class 129 (Fixed Position Class Ccc129). In HTML it can be written as ཱ or ཱ.