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An activation message is produced when a train entity is created from a schedule entity by the TRUST system. The train entity refers to a single run of a train on a specific day whereas the schedule entity is potentially valid for several months at a time. Within TRUST, this process is known as Train Call. Most trains are called automatically (auto-call) before the train is due to run, and there is no specific event which triggers the call. The exception to this is for schedules which are Runs as required, or Runs to terminals/yards as required (flagged with Q or Y in the schedule.) By default, it is assumed that the train will not run unless the train operator decides that it will; the train operator will submit a message to the TRUST system and this will then cause the schedule to be activated for that day (a process is known as manual call.)

Train activations are usually received 1 - 2 hours before the train is due to run, but these trains may be manually called earlier if some details of the train are due to change.

Data structure

Header

Field	Description
msg_type	'0001' for an activation message
source_dev_id	Always blank for an activation message
source_system_id	"TRUST" for an activation message
original_data_source	"TSIA" for an activation message

Body

Field	Description
train_id	The 10-character unique identity for this train This is used in other TRUST messages to identify the train. The train activation message links the train_id with a particular schedule. train_id is of the format nnHHHHsXXX where: nn is the first two digits of the origin TIPLOC, and represents the area where the train starts HHHH is the signalling ID (headcode) used within the data feeds to represent the train - for passenger trains this is the actual service headcode, but an obfusticated number is given for freight services. This is used by other feeds, e.g. the TD feed, to track trains. s is the speed class of the train (see speed classes.) XXX is three digits of uncertain meaning
creation_timestamp	The timestamp (in milliseconds since the UNIX epoch) when the train was originally created in TRUST
tp_origin_timestamp	The date, in YYYY-MM-DD format, that the train runs. For trains activated before midnight that run after midnight, this date will be tomorrow's date. Note: there is currently a problem with the tp_origin_timestamp field due to the truncation of the timestamp. This only occurs during daylight savings for trains which start their journey between 0001 and 0200 the next day. To work around this problem, use the date in the origin_dep_timestamp field.
train_uid	The unique ID of the schedule being activated - either a letter and five numbers, or a space and five numbers for VSTP trains
sched_origin_stanox	STANOX code for the originating location in the schedule
schedule_start_date	The start date of the schedule
schedule_end_date	The end date of the schedule
schedule_source	Set to C for schedules from CIF/ITPS, or V for schedules from VSTP/TOPS
schedule_type	Either C (Cancellation), N (New STP), O (STP Overlay) or P (Permanent i.e. as per the WTT/LTP)
schedule_wtt_id	The signaling ID (headcode) and speed class of the train
d1266_record_number	Either 00000 for a CIF/ITPS schedule, or the TOPS unique ID of the schedule
tp_origin_stanox	The STANOX code of the origin of the train If the train is due to start from a location other than the scheduled origin (i.e. it is part-cancelled), this will be the STANOX of the location at which the train starts. Otherwise it is the STANOX of the scheduled origin location. If this field is populated, it will be typically be in response to a VAR issued through VSTP or SCHEDULE.
origin_dep_timestamp	The estimated WTT time of departure from the originating location
train_call_type	Either AUTOMATIC for auto-called trains, or MANUAL for manual-called trains
train_call_mode	Set to NORMAL for a train called normally, or OVERNIGHT if the train is called as part of an overnight batch process to activate peak period trains early
toc_id	Operating company ID as per TOC Codes
train_service_code	Train service code as per schedule
train_file_address	The TOPS train file address, if applicable

Linking with Schedule Data

The train activation message is the only message type which directly links a signalling ID to a schedule. There are ways to infer this relationship using other data, but it is much more difficult.

An individual schedule is identified by the unique schedule identifier (train_uid) and the schedule start date (schedule_start_date). These will identify one or more schedules from the SCHEDULE data feed. If there are several schedules that have the same start date, then the one with the lowest STP indicator character is the valid one. Note: at present, there seems to be a bug in the schedule_type field which does not always match the schedules available in the SCHEDULE feed.