Creates a label of said name. You can use statements like goto to jump to this label.
The name can be made up of numbers (but not in the first position), 1-byte characters, and underscores, but nothing else.
ALLOWED ) *HAJIMARI
*Mike_Tom
*day01
NOT ALLOWED )*始まり (uses 2-byte chars)
*Mike&Tom (uses an ampersand)
*01day (number in the first position)