Modeling one-one and one-many relationships can be done via annotations, YAML, or XML. Using annotations, we can define multiple embedded subdocuments within our document:

/** @Document */
class User
{
   // ...
   /** @EmbedMany(targetDocument="Phonenumber") */
   private $phonenumbers = array();
   // ...
}
/** @EmbeddedDocument */
class Phonenumber
{
   // ...
}

Here a User document embeds many PhoneNumbers. @EmbedOne() will embed one subdocument to be used for modeling one-one relationships.

Referencing is similar to embedding:

/** @Document */
class User
{
   // ...
   /**
    * @ReferenceMany(targetDocument="Account")
    */
   private $accounts = array();
   // ...
}
/** @Document */
class Account
{
   // ...
}

@ReferenceMany() and @ReferenceOne() are used to model one-many and one-one relationships via referencing into a separate collection.