I have no idea how unicode domains are supposed to work but could it be something like

xpxr = 0x78 0x70 0x78 0x72
XPXR = 0x58 0x50 0x58 0x52

Unicode 7870 + 7872 or 5850 + 5852 don't seem to translate to anything of note though even with the two characters combined.

http://www.fileformat.info/info/unicode/char/7870/index.htm
http://www.fileformat.info/info/unicode/char/7872/index.htm

http://www.fileformat.info/info/unicode/char/5850/index.htm
http://www.fileformat.info/info/unicode/char/5852/index.htm