L2/15-165
Source: Mark Davis
Date: May 29, 2015
Subject:  Numeric properties for 218A/B
The following 2 items are Other_Symbol. 

U+218A ( ↊ ) TURNED DIGIT TWO
U+218B ( ↋ ) TURNED DIGIT THREE

I propose changing them to:

General Category = Other_Number
Numeric_Type = Numeric
Numeric_Value = 10 for 218A and 11 for 218B

====
The names list says that they are used as digits (in a base-12 system), as below. On that basis they should be General_Category=Other_Number. It appears that we have them as symbols because we didn't want to sanction their use. But we give a gazillion other things numeric values (http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5B%3ANo%3A%5D&g=nv); it doesn't mean ​that we use the clout of the Unicode Standard to promote any of them.

Turned digits

218A  ↊  TURNED DIGIT TWO
    digit for 10 in some duodecimal systems
218B  ↋  TURNED DIGIT THREE
    digit for 11 in some duodecimal systems
    0190 Ɛ latin capital letter open e
    2107 ℇ euler constant
    A72B ꜫ latin small letter tresillo