# ParameterDefinition
<a name="API_ParameterDefinition"></a>

Defines a parameter that a role template accepts. You supply values for these parameters when you create a role with [AcquireRole](https://docs.aws.amazon.com/IAM/latest/APIReference/API_AcquireRole.html).

## Contents
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 ** Name **   
The name of the parameter.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 128.  
Required: Yes

 ** Type **   
The data type of the parameter. Valid values are `String`, `StringList`, `Number`, `NumberList`, `Arn`, and `ArnList`.  
Type: String  
Valid Values: `String | StringList | Number | NumberList | Arn | ArnList`   
Required: Yes

 ** DefaultValue **   
The value that the service uses for the parameter when you do not supply one.  
Type: String  
Length Constraints: Maximum length of 1024.  
Required: No

 ** Description **   
A description of the parameter.  
Type: String  
Length Constraints: Maximum length of 1000.  
Required: No

 ** Immutable **   
Specifies whether you can change the parameter value after you create the role.  
Type: Boolean  
Required: No

 ** IsRequired **   
Specifies whether you must supply a value for the parameter when you create a role from the template.  
Type: Boolean  
Required: No

 ** SubType **   
An optional subtype that further constrains the values that are allowed for the parameter.  
Type: String  
Length Constraints: Maximum length of 256.  
Required: No

## See Also
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For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS SDK for C\+\+](https://docs.aws.amazon.com/goto/SdkForCpp/iam-2010-05-08/ParameterDefinition) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/iam-2010-05-08/ParameterDefinition) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/iam-2010-05-08/ParameterDefinition)