On principle, the features and examples contained in the document Accessing Data in an Adabas Database also apply to DL/I databases.
Differences, if any, are described in the documents for the individual database access statements (see the Statements documentation) in paragraphs named Database-Specific Considerations or in the documents for the individual Natural parameters (see the Parameter Reference).
For detailed information, refer to the following add-on product description in the Database Management System Interfaces documentation:
Natural for DL/I