Returns true (1) if the underlying data is valid. This will always be true (1) for simple types. For complex types (binary, dictionary and list) the underlying data may become invalid if owned by another object (e.g. list or dictionary) and that other object is then modified or destroyed. This value object can be re-used by calling Set*() even if the underlying data is invalid.

Returns true (1) if the underlying data is owned by another object.