Some file definitions do not contain all the implicit item definitions that exist in an application database. For example, an elementary data item in the file definition might be moved to a Working-Storage Section group item that is used to further subdivide the item for processing. Reference modification is another means of implicit redefinition or subdivision.
When it is necessary to expose these implicit subdivisions and redefinitions in the relational tables, the data items involved must be explicitly redefined within the Designer.