symfony - doctrine2 multiple level inheritance (4-5) -

Is it possible to create a 4-level inheritance in principle 2?

Something like this:

/ ** * @ORM \ mapped class class * / square person {} / ** * * * @ORM \ unit * @ ORM \ Table () * @ORM \ InheritanceType ("JOINED") * @ORM \ DiscriminatorColumn (name = "type", type = "string") * @ORM \ DiscriminatorMap ({'man_in_black' = "ManInBack"}) * / Square man extends person {} / ** * ???????? Line * / Class ManInblack Man {} / * * @ ORM \ Table () * @ORM \ unit () * Expands in / class Bob ManInBlack {} Expands {}

I understand Not really what's in the "??????????????????"