[i]<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
  <class name="Infobase.Core.Domain.User, ePos.Core" table="TLPOSAddressLoginIDs">
    <id name="LoginUid" column="EntryTLPOSAddressLoginID" type="Int32" >
      <generator class="native" />
    </id>
    <many-to-one name="Details"
                 class="Infobase.Core.Domain.UserDetails, ePos.Core"
                 column="UniqueTLPOSAddress"
                 cascade="all" unique="true"/>
  </class>
  <class name="Infobase.Core.Domain.UserDetails, ePos.Core" table="TLPOSAddresses" dynamic-update="true">
    <id name="Id" column="UniqueTLPOSAddress" type="Guid" >
      <generator class="guid"></generator>
    </id>
  </class>
</hibernate-mapping>[/i]

public class User {
    private int loginUid;
    private UserDetails details;

    public virtual int LoginUid {
        get { return loginUid; }
        set { loginUid = value; }
    }
   
    public virtual UserDetails Details {       
       get {
            if (details == null)
                details = new UserDetails();

            return details;
        }
        set { details = value;}
    }

}

public class UserDetails {
     private Guid id;

    private User user;

    public virtual Guid Id{
        get { return id; }
        set { id = value; }
    }
}