portion, OHWZ DE NQHS constitutes the entire call element. The call sign of the station called is OHWZ. For illustrative purposes, OHWZ is assumed to be the call sign for Commander Amphibious Squadron Three. Call signs in Navy messages reduce the length of transmission. Each ship, station, and command of the Navy (and of the other services) has one or more call signs, that are listed in various communication publications. Call signs are discussed in more detail later in this chapter. The prosign DE in the message stands for "from." It is used only in the call. Its complete meaning is "This transmission is from the station whose designation follows." It indicates the station actually transmitting the message or signal and only indicates the originator when the call is serving as the address. In the example, the calling station is NQHS, the international call sign of USS Blue Ridge (LCC 19). International call signs for U.S. Navy and U.S. Coast Guard ships begin with the letter N. In figure 3-2, transmission instructions consist of prosign T, meaning “Station called transmit this message to all addressees appearing in the address component.” OHWZ, therefore, is responsible for delivering the message to XGHL. If the T were immediately followed by call signs or address designations, it would assume the meaning of “‘Station called transmit this message to the addressees whose address designations follow.” Similarly, if the T were preceded and followed by call signs, it would mean ‘Station preceding T transmit this message to those addressees whose address designations follow T.” Other prosigns that may appear in transmission instructions are G (“Repeat back”), F (“Do not answer”), and L (“Relay”). Prosign G is used by a transmitting station to ensure that the receiving station has received the message as transmitted, particularly if the message is of great importance or of a type difficult to send or receive. If G appears alone in the transmission instructions, all stations called repeat back the message; if G is preceded by call signs, it means that stations whose call signs precede G repeat back the message. Prosign F means “Do not answer.” It is used in a method of visual signaling that will be discussed in chapter 4. Prosign L is the relay sign. Its meaning is similar to T, but is not as specific. In transmission instructions, L means “Relay to those addressees for whom you are responsible.” Its use also requires that the station called report to you that the 3-5 message has been relayed. The elements of the p r o c e d u r e  c o m p o n e n t  a r e  a s s i g n e d  b y communications personnel to effectively deliver the message or signal. The elements of the preamble, address, and prefix component, which follow, are released by the originator and are not altered by communications personnel. Preamble The preamble of a plaindress message shows its relative importance; contains the date-time group, by which most messages are identified; and provides information relating to the message. The preamble in figure 3-2 is P 061933Z MAR 95. P is a precedence prosign, and the remainder is the date-time group, including month and year, of transmission. The precedence assigned by an originator reflects a judgment as to the speed required to deliver the message to the addressee. By misusing the precedence system, you defeat its purpose, which is to assure rapid handling of message traffic over available facilities with a minimum of backlog and delay resulting from competing messages. The importance of a message does not necessarily imply urgency. Figure 3-4 shows the precedence categories, their speed-of-service objectives, and examples of their assignments. Messages having both action and information addressees may be assigned a single or dual precedence. If a single precedence is assigned to a multiple-address message, the precedence indicates the relative importance to all addressees. If assigned two precedences, one for action addressees and a lower precedence for information addressees, the message is of greater importance to the action addressees. If the message in figure 3-2 were assigned dual precedence, the preamble would read P R 061933Z MAR 95. This would show that the message should be treated as a priority message for delivery to OHWZ and as a routine message when delivered to XGHL. Dual-precedence messages, in visual signaling, normally are handled as single-precedence messages because of the proximity of ships and signaling stations. If, however, the action addressee of a dual-precedence (for example, P R) message were in company but one or more information addressees were not, relay would be required. In that instance, the message would be sent immediately to the action addressee, but might be transmitted to a different station for relay to the information addressees, using