A collection that is read-only does not allow the addition or removal of elements after the collection is created. Note that read-only in this context does not indicate whether individual elements of the collection can be modified, since the xtd::collections::generic::icollection <type_t> interface only supports addition and removal operations. For example, the IsReadOnly property of an array that is cast or converted to an xtd::collections::generic::icollection <type_t> object returns true, even though individual array elements can be modified.