 In the published Aufbau this abstemious bracketing policy is applied very strictly. Carnap adopts a principle of extensionality that does not exclude the use of intensional languages in auxiliary roles, but denies them any ultimate significance. Fregean “Sinn” (sense) is specifically excluded as merely psychological (§44), having only “epistemic value” but not “logical value” (§50), which is limited to the extensional meaning of an expression. Each step in the spelled-out constitution of the subjective (“autopsychological”) world is explained not only in logical symbols but also in a simple paraphrase, then in “realistic language” (as ordinarily used in science) and finally in a language of “fictive construction”. But Carnap makes clear that this is solely for convenience and to make the steps more transparent to readers. The four languages may differ not only in form but in their “Sinn”, their epistemic value (the different mental images they elicit), he says, though their logical value is always identical and is expressed most neutrally and clearly in the symbolic language (§95); for more detail, see the supplement  Aufbau.  