Mongolian Supplement is a Unicode block containing additional Mongolian letters not found in Mongolian block in BMP. It currently comprises nine variant forms of birga marks used to mark the start of text.
History The following Unicode-related documents record the purpose and process of defining specific characters in the Mongolian Supplement block:
Version Count L2 ID WG2 ID Document 9.0 U+11660..1166C 13 N4542 N4547 doc) N4632 doc)
References