AWS SDK for .NET Documentation
WorkflowId Property
AmazonAmazon.SimpleWorkflow.ModelStartChildWorkflowExecutionDecisionAttributesWorkflowId Did this page help you?   Yes   No    Tell us about it...
The workflowId of the workflow execution. This field is required. The specified string must not start or end with whitespace. It must not contain a : (colon), / (slash), | (vertical bar), or any control characters (\u0000-\u001f | \u007f - \u009f). Also, it must not contain the literal string "arn".

Constraints:

Length
1 - 256

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

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