Texas Instruments TI-83 PLUS - Manual (Page 313)

TI-83 Plus Lists 310
Ù need not precede a user-created list name where a list name is the
only valid input, for example, at the Name= prompt in the stat list editor or
the Xlist: and Ylist: prompts in the stat plot editor. If you enter Ù where it
is not necessary, the TI-83 Plus will ignore the entry.