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