capacity

The web ACL capacity units (WCUs) required for this rule group.

WAF uses WCUs to calculate and control the operating resources that are used to run your rules, rule groups, and web ACLs. WAF calculates capacity differently for each rule type, to reflect the relative cost of each rule. Simple rules that cost little to run use fewer WCUs than more complex rules that use more processing power. Rule group capacity is fixed at creation, which helps users plan their web ACL WCU usage when they use a rule group. For more information, see WAF web ACL capacity units (WCU) in the WAF Developer Guide.