What is the test for total revocation of a suspect's Fifth Amendment right to remain silent?

Total revocation, of course, requires only that the individual indicate in some manner that he wishes to remain silent. Miranda v. Arizona, 384 U.S. 436, 473-74, 86 S.Ct. 1602, 16 L.Ed.2d 694 (1966). Selective exercise of the right to remain silent was accomplished in Egger, by contrast, by the suspect's initial, express declaration that such was his intent. It may well be that the selective exercise of one's Fifth Amendment rights or at least a selective revocation of an earlier complete waiver of those rights requires that some kind of communication to that effect be made to the questioning officers. Since this issue is not before us, however, we do not decide it.