The WhoAmISubResponseDataOptionalAttributes attribute group contains attributes that MUST be used only in SubResponseData elements associated with a subresponse for a Who Am I subrequest. The attributes in WhoAmISubResponseDataOptionalAttributes provide the data that was requested as part of the Who Am I subrequest. The schema definition of the WhoAmISubResponseDataOptionalAttributes attribute group is as follows:

 <xs:attributeGroup name="WhoAmISubResponseDataOptionalAttributes">
     <xs:attribute name="UserName" type="tns:UserNameType" use="optional"/>
     <xs:attribute name="UserEmailAddress" type="xs:string" use="optional"/>
     <xs:attribute name="UserSIPAddress" type="xs:string" use="optional" />
     <xs:attribute name="UserIsAnonymous" type="xs:boolean" use="optional" />
     <xs:attribute name="UserLogin" type="xs:UserLoginType" use="required" />

UserName: A UserNameType that specifies the user name for the protocol client. UserNameType is defined in section

UserEmailAddress: A string that specifies the email address associated with the protocol client. The format of the email address MUST be as specified in [RFC2822] section 3.4.1.

UserSIPAddress: A string that specifies the Session Initiation Protocol (SIP) address associated with the protocol client.

UserIsAnonymous: A Boolean value that specifies whether the protocol client is an anonymous guest user. Protocol servers SHOULD return TRUE if the user is an anonymous guest user.<39>

UserLogin: A UserLoginType that specifies the user login alias of the protocol client. UserLoginType is defined in section The UserLogin attribute MUST be specified in a WhoAmI subresponse that is generated in response to a WhoAmI subrequest.