trailName 
  Specifies the name of the trail or trail ARN. If you specify a trail name, the string must meet the following requirements:
- Contain only ASCII letters (a-z, A-Z), numbers (0-9), periods (.), underscores (_), or dashes (-) 
- Start with a letter or number, and end with a letter or number 
- Be between 3 and 128 characters 
- Have no adjacent periods, underscores or dashes. Names like - my-_namespaceand- my--namespaceare not valid.
- Not be in IP address format (for example, 192.168.5.4) 
If you specify a trail ARN, it must be in the format:
arn:aws:cloudtrail:us-east-2:123456789012:trail/MyTrail