In Russell's writings of the period between 1905 and 1918, a logically proper name is a term whose true logical role is to refer to an object. A cluster of considerations led Russell to believe that ordinary names function differently, as definite descriptions in disguise, and that only items with which we are directly acquainted could strictly be named. These would be items presented in current experience. A logically proper name is a tag for such an item. There are, however, not many kinds of them, since relatively few types of item qualify as elements of immediate experience. They include the self (perhaps), the present time, sense data, and universals. See also logical atomism.