U+A827 Syloti Nagri Vowel Sign Oo

The Wikipedia has the following information about this codepoint:

Sylheti Nagri or Sylheti Nāgarī (Sylheti: ꠍꠤꠟꠐꠤ ꠘꠣꠉꠞꠤ, síloṭi nagri, pronounced [sílɔʈi nagɾi]), known in classical manuscripts as Sylhet Nagri (ꠍꠤꠟꠦꠐ ꠘꠣꠉꠞꠤ) as well as by many other names, is an Indic script of the Brahmic family. The script was historically used in the regions of Bengal and Assam, that were east of the Padma. It was primarily used in the eastern part of the Sylhet region, to document poetry known as puthis. In the course of the 20th century, it has lost much ground to the standardised Eastern Nagari script. Printing presses for Sylheti Nagri existed as late as into the 1970s, and in the 2000s, a Unicode font was created for the script.

Historically the script was transcribed in Middle Bengali, though having similar characteristics to the more popular Dobhashi literary dialect, it was distinguished for its phonological influence from the Sylheti language. It is also claimed that the orthography of the script equates with Sylheti, reflecting the language's phonetic and grammatical features, it provided a simpler and more precise representation than the prevalent Bengali script. Sylheti Nagri therefore represented a unique literary culture of the Sylhet region. Contemporarily, the script is being revived by some as a key identity marker of Sylhet's cultural heritage, and as a means to write in the Sylheti language.