COBOL copybooks can define multiple record layouts. The layout of each data record is often determined by a record ID (RID) field.
The following types of redefinitions in a COBOL copybook define multiple record layouts:
REDEFINE statements
Multiple 01 levels that define multiple record types
The createdatamaps utility can generate data maps for COBOL copybooks that include REDEFINE statements, multiple 01 levels, or both. And you can configure the control file so that the utility finds RID fields and associates RID values with data records.