Alist of scripts vs the representative characters.
Each element is a cons (SCRIPT . CHARS).
SCRIPT is a symbol representing a script or a subgroup of a script.
CHARS is a list or a vector of characters.
If it is a list, all characters in the list are necessary for supporting SCRIPT.
If it is a vector, one of the characters in the vector is necessary.
This variable is used to find a font for a specific script.