How to write row:contact_* variable?

Hello, please tell me where to look for "variable key according to document variables for contacts" for row:contact_* variable in document templates? The "Process Contacts" block is displayed in the process, a contact is added to it, but when you try to print certain contact data (additional contact field) for printing, nothing is displayed in the document template. The data is allowed to be used in the template (the checkbox prohibiting the use is not set and is not even displayed for display). In what form should the variable be written if the identifier of the additional contact field is, for example, INN? https://prnt.sc/ui75da Task with block (top): https://zavod.crm-onebox.com/admin/customorder/test/209460/edit/#done Printing a document by clicking the "Issue an external invoice" button Document template (I set the variable at the top right): https://zavod.crm-onebox.com/admin/shop/document/templates/29/control/ Variable reference: https://zavod.crm-