Set field

Writes a value into a field of the event type.

Configuration	Content
Destination	field of the event type
Value	fixed value or expression, validated according to the field type

It is the most common action. Typical uses: flagging a transaction for review, classifying an event, or recording the risk band assigned to it.

Condition:  $amount > 10000 and $issuer_country != "BR"
Action:     Set field → review = "true"          (fixed value)

In expression mode, the value written comes from another field, from a temporary variable, or from a join. This mode carries a result computed during the rule into the event. It is also the way to write the reading of a producing action, as described in Published results:

Condition:  $amount > 0                    → Run analysis: bot
Condition:  %bot.triggered == true         → Set field: bot_score = %bot.score   (expression)

The platform validates the value when the rule is saved, according to the destination field’s rules: a numeric field does not accept text, a text field respects the configured size. Fields reserved by the platform (starting with _) cannot be filled in by an action.

When the destination is a boolean field, the fixed value is chosen from a list with the field’s own two labels: you select Blocked, not true. To copy a boolean from somewhere else, such as %bot.triggered, use expression mode.

The written value persists in the event. If two conditions fill in the same field, the last one executed wins.