Pokrytie
Pokrytie is one of the historic diacritical signs of Cyrillic that was used in Old [Church Slavonic], later medieval Cyrillic literary traditions and modern Church Slavonic.
It is a modification of titlo adapted for covering combining Cyrillic letters. It is conventionally not used with combining modifications of letters Д, Ж, З and Х, although exceptions happen, especially in skoropis.
The character was introduced into Unicode 5.1 in April 2008.