Abstract OpenID Attribute Exchange is an OpenID service extension for exchanging identity information between endpoints. Messages for retrieval and storage of identity information are provided. Table of Contents 1. Terminology 1.1. Definitions and Conventions 2. Overview 3. Information Model 3.1. Subject Identifier 3.2. Attribute Type Identifier 3.3. Attribute Value 3.3.1. Attribute-Specific Encod