//товар
Class MyProject.Good Extends %Persistent
{
Property NameRus As %String;
Property Price As %Float;

Relationship InvoiceItems As MyProject.InvoiceItem [ Cardinality = many, Inverse = MyGood];
}

//накладная
Class MyProject.Invoice Extends %Persistent
{
Property InvoiceDate As %TimeStamp;
Property Number As %String;

Relationship Items As MyProject.InvoiceItem [ Cardinality = many, Inverse = MyInvoice];

}

//позиция накладной
Class MyProject.InvoiceItem Extends %Persistent
{
//ссылка на товар
Relationship MyGood As MyProject.Good [ Cardinality = one, Inverse = InvoiceItems ];
//ссылка на накладную
Relationship MyInvoice As MyProject.Invoice [ Cardinality = one, Inverse = Items];
Property Count As %Integer;
}

//товар
Class MyProject.Good Extends %Persistent
{
Property NameRus As %String;
Property Price As %Float;
}

//накладная
Class MyProject.Invoice Extends %Persistent
{
Property InvoiceDate As %TimeStamp;
Property Number As %String;

//массив позиций
Property Items As list Of MyProject.InvoiceItem;
}

//позиция накладной
Class MyProject.InvoiceItem Extends %SerialObject
{
//ссылка на товар
Property Good As MyProject.Good;
Property Count As %Integer;
}