I have seen in a few places the following. e.g., DoInvFormTool.hal:
external outer procedure DoInvFormRowCustomizedFields(record IVVc,row IVVc,record DocVc,record SysFormatBlock,record RoundBlock,record LangNrVc,Boolean);

As far as I understand DoInvForm.hal is in level zero, why the code tries to execute a procedure in level 3? Anyway this procedure is empty.