Making existing non-LANSA files known to LANSA
If you are extending an existing application, such as a third party package, you need to make the application's file definitions known to LANSA. This is done using a process called "loading the definition" which creates field definitions and physical and logical file definitions from your existing files. File definitions can be loaded one by one as described in 5.2 Make non-LANSA IBM i Files known to LANSA or as a bulk load as described in 5.2.3 Load (or Re-load) Multiple File Definitions.
After loading the file definitions, you can add validation logic, as well as virtual fields, field descriptions, column headings, defaults, help text, etc.
Files maintained by non-LANSA applications are sometimes referred to as "external" or "other" files within the LANSA system.
Defining new files manually
Before a new file is created using LANSA, the fields within the file must first be defined. Field descriptions, column headings, defaults, help text, etc. should be added before the file is created. Field details can, of course, be finalized after the file is created, as is done when creating files from "external" files. Refer to 5.3 Manually Create New Files with LANSA for the steps needed to create new files.