the medical attaché receives the cartridge — "the return-address box has only the…"

The Entertainment's calling card is a smile with no sender. Where identifying information should be — return address, logo, the codes normally embossed on the cartridge itself — there is only a crude grinning face, and the same circular smiling head shows up embossed on the disk where the registration and duration codes belong. It is the smiley-emblem the A.F.R. and the samizdat keep leaving as a signature (it recurs on the junk-shop shelf at 097, "one need no longer pursue happiness"), and its meaning is exactly its anonymity: the master doesn't need to name itself, it only needs to smile and be inserted. The blankness is the threat.