¿Qué significa coat of arms ?

Confused by her encounters, Oedipa goes back to Fallopian to try to piece things together. They cannot draw any connections, although Fallopian sees a connection between Indian killers and the Wells, Fargo, and Pony Express mail delivery systems he is currently researching. Feeling unsatisfied, Oedipa goes to Genghis Cohen, a philatelist (a stamp expert) who has been hired to oversee Pierce's stamp collection. Genghis tells Oedipa that he has contracted an Expert Committee to examine some of Pierce's more problematic, confusing stamps. These "problem stamps," he shows Oedipa, all have a muted post horn as a watermark. Genghis also shows Oedipa that German stamps from the time of the Thurn and Taxis era have the same marking, which is a symbol in the Thurn and Taxis coat of arms (without the mute, of course). Oedipa recalls the line from The Courier's Tragedy, "And tacit lies the gold once-knotted horn," which she believes related to the efforts of the Tristero to silence Thurn and Taxis. She realizes that the trapezoid is definitely a mute; she thinks that someone is trying to mute the postal horn.