Field,Field Description,Length,Position,Notes
1,Record Identity,2,1-2,With the constant value ‘AA’.
2,Transaction Type,1,3-3,‘N’ = New. ‘D’ = Delete. ‘R’ = Revise.
3,Base UID,6,4-9,"One of the trains involved in the association. This will always be the through train, not the splitting/joining portion."
4,Assoc UID,6,10-15,The other train involved.
5,Assoc Start date,6,16-21,Format: yymmdd. May not be the same as the dates of the train schedules.
6,Assoc End date,6,22-27,Format: yymmdd. May not be the same as the dates of the train schedules.
7,Assoc Days,7,28-34,
8,Assoc Cat,2,35-36,"The ASSOC-CAT for the base UID (first byte), followed by the ASSOC-CAT for the assoc. UID (second byte). Note: Although this field isn’t specified as having blanks in the Network Rail CIF specification, if blanks are supplied they will be carried forward. (Blanks are used to override the permanent value in overlays and cancellations). ‘JJ’ for Joining trains and ‘VV’ for Dividing trains. ‘NP’ for Next/Previous Associations may also be displayed but as this is an Operating association it should be ignored by journey planners."
9,Assoc Date Ind,1,37-37,"‘S’ = Standard. ‘N’ = Over-next-midnight. ‘P’ = Over-previous-midnight. Note: Although this field isn’t specified as having blanks in the Network Rail CIF specification, if blanks are supplied they will be carried forward. (Blanks are used to override the permanent value in overlays and cancellations)."
10,Assoc Location,7,38-44,TIPLOC where association occurs.
11,Base Location Suffix,1,45-45,Values are space or 2.
12,Assoc Location Suffix,1,46-46,Values are space or 2.
13,Diagram Type,1,47-47,With the constant value ‘T’.
14,Association Type,1,48-48,"‘P’ = Passenger use. ‘O’ = Operating use. Note: Although this field isn’t specified as having blanks in the Network Rail CIF specification, if blanks are supplied they will be carried forward. (If blank then association defaults to Operating and should be ignored by journey planners)."
15,Filler,31,49-79,
16,STP indicator,1,80-80,Read in conjunction with the ‘Transaction Type’ in Field 2. ‘C’ = STP cancellation of permanent schedule. ‘N’ = New STP schedule. ‘O’ = STP overlay of permanent schedule. ‘P’ = Permanent.