| Segment | Ebene | Beschreibung | Opt/Mand. |
|---|
| UIH | 0 | A service segment starting and uniquely identifying a message. The message type code for the Schedule update - interactive message is SKDUPD. Note: Schedule update - interactive messages conforming to this document must contain the following data in segment UIH, composite S306: Data element 0065 SKDUPD D A UN | Mandatory |
| MSD | 0 | A segment to specify the type and business function of the message. | Mandatory |
| ORG | 0 | A segment to specify details related to the originator of the schedule update. | Mandatory |
| HDR | 0 | A segment to specify information applicable to the entire message. | Mandatory |
| IFT | 0 | A segment to provide free text information relating to the entire message. | Optional |
| RFR | 0 | A segment to specify a reference relating to the entire message. | Optional |
| SG1 | 0 | SG1 | Optional |
| ERI | 1 | A segment to specify the type of application error. | Mandatory |
| RFR | 1 | A segment to reference the erroneus element. | Optional |
| IFT | 1 | A segment to provide text related to the error. | Optional |
| SG2 | 0 | SG2 | Optional |
| PRD | 1 | A segment to specify a transport service. | Mandatory |
| PDT | 1 | A segment to provide detail information about the service. | Optional |
| IFT | 1 | A segment to provide free text information relating to the service. | Optional |
| TRF | 1 | A segment identifying restrictions applicable to the service. | Optional |
| ASD | 1 | A segment to provide information about extra services included in the service | Optional |
| MSD | 1 | To specify the action to be applied on the associated service. | Optional |
| RFR | 1 | A segment used to specify a travel service number which is published to the customer | Optional |
| SG3 | 1 | SG3 | Optional |
| SER | 2 | A segment specifying additional service information. | Mandatory |
| ASD | 2 | A segment to provide information about extra services included in the facility. | Optional |
| SG4 | 1 | SG4 | Optional |
| POP | 2 | A segment to specify a period of operation of the service. | Mandatory |
| PDT | 2 | A segment to provide detail information about the service. | Optional |
| IFT | 2 | A segment to provide free text information relating to the service. | Optional |
| TRF | 2 | A segment identifying restrictions applicable to the service. | Optional |
| ASD | 2 | A segment to provide information about extra services included in the service. | Optional |
| FRQ | 2 | A segment to specify details about the frequency of the service. | Optional |
| SG5 | 2 | SG5 | Optional |
| SER | 3 | A segment specifying additional service information. | Mandatory |
| ASD | 3 | A segment to provide information about extra services included in the service. | Optional |
| SG6 | 2 | SG6 | Optional |
| DTI | 3 | To identify a day or period to be included in or excluded from the period of operation of the service. | Mandatory |
| IFT | 3 | To specify a free text description of the day or period. | Optional |
| SG7 | 2 | SG7 | Optional |
| POR | 3 | A segment specifying a location and the service times related to this location. | Mandatory |
| MES | 3 | A segment to specify measurement values relating to the service at the given location. | Optional |
| ASD | 3 | A segment to provide information about extra services included in the service and relating to the location. | Optional |
| SER | 3 | A segment specifying additional service information relating to the location. | Optional |
| TRF | 3 | A segment identifying restrictions applicable to the service at the given location. | Optional |
| SG8 | 3 | SG8 | Optional |
| RFR | 4 | A segment to specify a reference to another service. | Mandatory |
| RLS | 4 | A segment to specify the type of relation. | Optional |
| TCE | 4 | A segment to specify details about the connection conditions to another service. | Optional |
| SG9 | 2 | SG9 | Optional |
| ODI | 3 | A segment to specify the origin and destination locations of a service leg or segment. | Mandatory |
| PDT | 3 | A segment to provide detail information about the service leg or segment. | Optional |
| IFT | 3 | A segment to provide free text information relating to the service leg or segment. | Optional |
| TRF | 3 | A segment identifying restrictions applicable to the service leg or segment. | Optional |
| TFF | 3 | A segment to specify tariff information related to the service leg or segment. | Optional |
| ASD | 3 | A segment to provide information about extra services included in the service. | Optional |
| SG10 | 3 | SG10 | Optional |
| SER | 4 | A segment specifying additional service information. | Mandatory |
| ASD | 4 | A segment to provide information about extra services included in the service. | Optional |
| UIT | 0 | A service segment ending a message, giving the total number of segments in the message (including the UIH & UIT) and the control reference number of the message. | Mandatory |
