the HTTP header name and value. The actual
encoding scheme will be decided later.</p><table class=message-fields><thead><tr><th>Field</th><th>Type</th><th>Description</th></tr></thead><tbody><tr id=AttributeManifest-AttributeInfo-description><td><code>description</code></td><td><code>string</code></td><td><p>Optional. A human-readable description of the attribute&rsquo;s purpose.</p></td></tr><tr id=AttributeManifest-AttributeInfo-value_type><td><code>valueType</code></td><td><code><a href=#ValueType>ValueT