GENERAL INSTRUCTIONS 



1241. The coded weather message will be copied from Form 615-5 to 

 Form 630-9. 



1250. CODE FOR TRANSMISSION. Weather messages will be encoded 

 in the International Code for Radio Weather Reports from Ships, as indicated 

 below. Each element in the coded weather observation message is indicated 

 by one or more symbol letters. The symbolic form of the code (FM21A) is 

 as follows: 



YQLaLaLa LoLoLoGG Nddff VVwwW PPPTT 

 NhCLhCMCn Ds^s^PP OT^T^TdTd Id^d^P^H^ 

 ICE C2KD.re 



Additional groups may be added in accordance with paragraphs 6431 and 9410. 



1251. The symbols of the ship's code are listed and defined in Table 

 1-1 in the order of their appearance in the message. The relevant paragraphs 

 and code tables in this manual are listed in adjacent columns. 



1252. The "c2KDire" group is used to report ice. When it is included, 

 it must be preceded by the identifying word, "ICE." 



1253. When the data for an element of the message cannot be determined, 

 the letter "X" will be substituted as required by the code table appropriate 

 to the missing data. Each group will then be composed of five characters, 

 either numerals or X's. If data for an entire group is missing from the 

 first seven groups of the message, five X's(XXXXX) will be reported for that 

 group. 



1253.1. When the seventh group (DgVgapp) is omitted from the message, 

 30 will be added to the time in coding GG. A group of five X's will not be 

 sent to indicate a missing seventh group. 



1253.2. When the sixth group (NhCLhCjy|-Cj^) and the seventh group 

 (DgVgapp) are omitted, 60 will be added to the time in coding GG. Groups 

 of five X's will not be sent to indicate missing sixth and seventh groups. 



1253.3 When all the elements of one of the groups OTgTgT(jTf}, IdwdwPwH-w 

 ICE C2KDire are missing, that group will be omitted from the coded message. 

 Five X's will not be sent to indicate missing groups. 



664508 O - 62 - 



