about property annotation some question

i read Phosphorum code , See this code in PostsPollOptionsfile.

  /**
 * Post's Poll Options Model
 *
 * @property Posts post
 *
 * @method static PostsPollOptions findFirstById(int $id)
 * @method Posts getPost($parameters = null)
 *
 * @package Phosphorum\Models
 */

It is not a note ,You can actually use.... but i not found the related documents..help...