<?php return array( 'type' => 'object', 'properties' => array( 'resource' => array( 'type' => 'string', 'const' => 'url', 'description' => 'Identifies the file resource as a URL', ), 'url' => array( 'type' => 'string', 'description' => 'The URL of the file', ), 'caption' => array( 'type' => 'string', 'description' => 'Optional caption for displaying a progress message', ), ), 'required' => array( 'resource', 'url', ), 'additionalProperties' => false, );