DECEASED/INACTIVE/NO_VALID_ADDRESSES/ANONYMOUS are Boolean fields.  As The Raiser's Edge is built with Microsoft technology, it adopts Microsoft's representation of Boolean datatypes.  When The Raiser's Edge was first developed, this meant:
0 = false
-1 = true

Microsoft describes the Boolean datatype with .NET and numeric type conversions in:
https://docs.microsoft.com/en-us/dotnet/visual-basic/language-reference/data-types/boolean-data-type

All Boolean fields in The Raiser's Edge database are stored like this.