# RateLimitLabelNamespace
<a name="API_RateLimitLabelNamespace"></a>

Specifies a label namespace to use as an aggregate key for a rate-based rule. Each distinct fully qualified label name that has the specified label namespace contributes to the aggregation instance. If you use just one label namespace as your custom key, then each label name fully defines an aggregation instance. 

This uses only labels that have been added to the request by rules that are evaluated before this rate-based rule in the web ACL. 

For information about label namespaces and names, see [Label syntax and naming requirements](https://docs.amazonaws.cn/waf/latest/developerguide/waf-rule-label-requirements.html) in the * Amazon WAF Developer Guide*.

## Contents
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 ** Namespace **   <a name="WAF-Type-RateLimitLabelNamespace-Namespace"></a>
The namespace to use for aggregation.   
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 1024.  
Pattern: `^[0-9A-Za-z_\-:]+:$`   
Required: Yes

## See Also
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For more information about using this API in one of the language-specific Amazon SDKs, see the following:
+  [Amazon SDK for C\$1\$1](https://docs.amazonaws.cn/goto/SdkForCpp/wafv2-2019-07-29/RateLimitLabelNamespace) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/wafv2-2019-07-29/RateLimitLabelNamespace) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/wafv2-2019-07-29/RateLimitLabelNamespace)