• The AWS Systems Manager CloudWatch Dashboard will no longer be available after April 30, 2026. Customers can continue to use Amazon CloudWatch console to view, create, and manage their Amazon CloudWatch dashboards, just as they do today. For more information, see [Amazon CloudWatch Dashboard documentation](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CloudWatch_Dashboards.html). 

# Understanding parameter name requirements and constraints
<a name="sysman-parameter-name-constraints"></a>

Use the information in this topic to help you specify valid values for parameter names when you create a parameter. 

This information supplements the details in the topic [PutParameter](https://docs.aws.amazon.com/systems-manager/latest/APIReference/API_PutParameter.html) in the *AWS Systems Manager API Reference*, which also provides information about the values **AllowedPattern**, **Description**, **KeyId**, **Overwrite**, **Type**, and **Value**.

The requirements and constraints for parameter names include the following:
+ **Case sensitivity**: Parameter names are case sensitive.
+ **Spaces**: Parameter names can't include spaces.
+ **Valid characters**: Parameter names can consist of the following symbols and letters only: `a-zA-Z0-9_.-`

  In addition, the slash character ( / ) is used to delineate hierarchies in parameter names. For example: `/Dev/Production/East/Project-ABC/MyParameter`
+ **Valid AMI format**: When you choose `aws:ec2:image` as the data type for a `String` parameter, the ID you enter must validate for the AMI ID format `ami-12345abcdeEXAMPLE`.
+ **Fully qualified**: When you create or reference a parameter in a hierarchy, include a leading forward slash character (/) . When you reference a parameter that is part of a hierarchy, specify the entire hierarchy path including the initial slash (/).
  + Fully qualified parameter names: `MyParameter1`, `/MyParameter2`, `/Dev/Production/East/Project-ABC/MyParameter`
  + Not fully qualified parameter name: `MyParameter3/L1`
+ **Length**: The maximum length for a parameter name that you specify is 1011 characters. This count of 1011 characters includes the characters in the ARN that precede the name you specify, such as the 45 characters in `arn:aws:ssm:us-east-2:111122223333:parameter/`.
+ **Prefixes**: A parameter name can't be prefixed with "`aws`" or "`ssm`" (case-insensitive). For example, attempts to create parameters with the following names fail with an exception:
  + `awsTestParameter`
  + `SSM-testparameter`
  + `/aws/testparam1`
**Note**  
When you specify a parameter in an SSM document, command, or script, include `ssm` as part of the syntax. For example, {{ssm:{{parameter-name}}}} and {{ ssm:{{parameter-name}} }}, such as `{{ssm:MyParameter}}`, and `{{ ssm:MyParameter }}.`
+ **Uniqueness**: A parameter name must be unique within an AWS Region. For example, Systems Manager treats the following as separate parameters, if they exist in the same Region:
  + `/Test/TestParam1`
  + `/TestParam1`

  The following examples are also unique:
  + `/Test/TestParam1/Logpath1`
  + `/Test/TestParam1`

  The following examples, however, if in the same Region, aren't unique:
  + `/TestParam1`
  + `TestParam1`
+ **Hierarchy depth**: If you specify a parameter hierarchy, the hierarchy can have a maximum depth of fifteen levels. You can define a parameter at any level of the hierarchy. Both of the following examples are structurally valid:
  + `/Level-1/L2/L3/L4/L5/L6/L7/L8/L9/L10/L11/L12/L13/L14/parameter-name`
  + `parameter-name`

  Attempting to create the following parameter would fail with a `HierarchyLevelLimitExceededException` exception:
  + `/Level-1/L2/L3/L4/L5/L6/L7/L8/L9/L10/L11/L12/L13/L14/L15/L16/parameter-name`

**Important**  
If a user has access to a path, then the user can access all levels of that path. For example, if a user has permission to access path `/a`, then the user can also access `/a/b`. Even if a user has explicitly been denied access in AWS Identity and Access Management (IAM) for parameter `/a/b`, they can still call the [GetParametersByPath](https://docs.aws.amazon.com/systems-manager/latest/APIReference/API_GetParametersByPath.html) API operation recursively for `/a` and view `/a/b`.