AWS SDK for .NET Documentation
Cause Property
AmazonAmazon.SimpleWorkflow.ModelWorkflowExecutionTerminatedEventAttributesCause Did this page help you?   Yes   No    Tell us about it...
If set, indicates that the workflow execution was automatically terminated, and specifies the cause. This happens if the parent workflow execution times out or is terminated and the child policy is set to terminate child executions.

Constraints:

Allowed Values
CHILD_POLICY_APPLIED, EVENT_LIMIT_EXCEEDED, OPERATOR_INITIATED

Declaration Syntax
C#
public string Cause { get; set; }

Assembly: AWSSDK (Module: AWSSDK) Version: 1.5.60.0 (1.5.60.0)