2003 UB313 is often confused with Eris.
Mispelled spelling on 2003 UB311.
2003 UB313 IS Eris.
2003 UB311 exists. If you didn't know 1950 DA has a partner 1950 DB, DC, DD...
2003 UB312 and 314 exist too.
Asteroids get named...
the first letter is the two week part
2009 BT5 for example.
B is the 2nd 2 week segment of 2009. then they go...
BA. BB, BC, BD, BE, BF, BH, BJ (yes, they skip "I")... BX, BY, BZ, BA1, BB1, BC 1... BA2, BB2...
If you calculate, There cannot be a 2008 ZW! As there is only room to Y (if "I" isn't used). By there can be a 2008 YZ!