string designator: n. a designator for a string; that is,
an object that denotes a string
and that is one of:
a character (denoting a singleton string
that has the character as its only element),
a symbol (denoting the string that is its name),
or a string (denoting itself).
The intent is that this term be consistent with the behavior of string;
implementations that extend string must extend the meaning of
this term in a compatible way.
string equal: adj.
the same under string-equal.