If a program contained the following definition:
01 rec.
03 forename pic X(10).
03 personnel-no pic X(4).
03 surname pic X(15).
the syntax:
record key is fullname = surname forename
would cause the COBOL system to treat fullname as though it were an explicitly defined group item consisting of:
03 surname pic X(15).
03 forename pic X(10).