in freemarker-core/src/main/misc/identifierChars/src/main/freemarker/adhoc/IdentifierCharGenerator.java [147:160]
private static boolean isXML11NameStartChar(int i) {
return i == ':' || (i >= 'A' && i <= 'Z') || i == '_' || (i >= 'a' && i <= 'z')
|| i >= 0xC0 && i <= 0xD6
|| i >= 0xD8 && i <= 0xF6
|| i >= 0xF8 && i <= 0x2FF
|| i >= 0x370 && i <= 0x37D
|| i >= 0x37F && i <= 0x1FFF
|| i >= 0x200C && i <= 0x200D
|| i >= 0x2070 && i <= 0x218F
|| i >= 0x2C00 && i <= 0x2FEF
|| i >= 0x3001 && i <= 0xD7FF
|| i >= 0xF900 && i <= 0xFDCF
|| i >= 0xFDF0 && i <= 0xFFFD;
}