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# Parameter Attributes
The following attributes apply to parameters of a method in a class or interface.  
  
|Attribute|Description|  
|---------------|-----------------|  
|[custom](../windows/custom-cpp.md)|Lets you define your own attribute.|  
|[defaultvalue](../windows/defaultvalue.md)|Allows specification of a default value for a typed optional parameter.|  
|[first_is](../windows/first-is.md)|Specifies the index of the first array element to be transmitted.|  
|[iid_is](../windows/iid-is.md)|Specifies the index of the first array element to be transmitted.|  
|[immediatebind](../windows/immediatebind.md)|Indicates that the database will be notified immediately of all changes to a property of a data-bound object.|  
|[in](../windows/in-cpp.md)|Indicates that a parameter is to be passed from the calling procedure to the called procedure.|  
|[last_is](../windows/last-is.md)|Specifies the index of the last array element to be transmitted.|  
|[lcid](../windows/lcid.md)|Lets you pass a locale identifier to a function.|  
|[length_is](../windows/length-is.md)|Specifies the number of array elements to be transmitted.|  
|[max_is](../windows/max-is.md)|Designates the maximum value for a valid array index.|  
|[optional](../windows/optional-cpp.md)|Specifies an optional parameter for a member function.|  
|[out](../windows/out-cpp.md)|Identifies pointer parameters that are returned from the called procedure to the calling procedure (from the server to the client).|  
|[range](../windows/range-cpp.md)|Specifies a range of allowable values for arguments or fields whose values are set at run time.|  
|[ref](../windows/ref-cpp.md)|Identifies a reference pointer.|  
|[retval](../windows/retval.md)|Designates the parameter that receives the return value of the member.|  
|[satype](../windows/satype.md)|Specifies the data type of the **SAFEARRAY** structure.|  
|[size_is](../windows/size-is.md)|Specifies the size of memory allocated for sized pointers, sized pointers to sized pointers, and single- or multidimensional arrays.|  
|[unique](../windows/unique-cpp.md)|Specifies a unique pointer.|  
  
## See Also  
 [Attributes by Usage](../windows/attributes-by-usage.md)