In the following example, compilation would result in two classes named grp1. To fix the error, rename one of the 01 level items.
$set ilsmartlinkage
program-id a.
linkage section.
01 grp1. *> rename one of these items
03 nam pic x(20).
procedure division using grp1.
...
end program.
program-id b.
linkage section.
01 grp1. *> rename one of these items
03 num pic 9(9).
procedure division using grp1.
...
end program.