How to model Entity A contains Entity B

I'm trying to model, for the purposes of XSD schema generation, the following pseudo XSD code,

complexType name="Account" ...

complexType name="Ledger"
  sequence
   element name="accnt" type="Account"


so that Ledger contains a whole instance/copy of Account. ER Studio works well and is suggestive on how to model Ledger having a reference to Account (or vice-versa) once PKs are defined. But that's not what I am looking for.