. JTA —Station/channel designator letters;
. xxx —Three-digit number indicating the
sequential number of transmissions.
The station/channel designators vary for each
channel and are determined by the status of the
originating station. For example, if a minor relay or
tributary station originates a TI to a major relay station,
the first two characters consist of the fifth and sixth
letters of the station routing indicator. The third
character identifies the channel. Channel designators
start with the letter A, progress alphabetically, and are
assigned to all connected channels. For example, a
tributary station having the routing indicator
RUWTABA would use the designator “ABA” for the
first outgoing channel and “ABB,” “ABC,” and so on,
for additional outgoing channels.
MESSAGE HEADER (FORMAT LINE
2). —The message header is a basic 43-position header
(figure 1-2). The message header is the starting point
for the operator who is preparing the message tape.
When preparing the header, the operator must
remember that it must be letter-perfect.
The following paragraphs describe each position of
the header:
Position 1 (Precedence) —The prosign Z
(FLASH), O (IMMEDIATE), P (PRIORITY), or R
Figure 1-2.—Message header (format line 2).
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