COBRT096 Invalid use of fork() (Fatal) You have called the operating system's fork() API in a process that has called COBOL functionality, or has multiple threads, and then called some COBOL functionality in
the child process.
COBRT099 Illegal operation in SORT/MERGE module (Fatal) A SORT or MERGE module has received a RELEASE operation outside the Input procedure, or a RETURN operation either outside
the Output procedure, or before the Input procedure has terminated correctly.
COBRT100 Invalid file operation (Fatal) You have tried a file operation which violates a general rule of COBOL in some way. The most likely cause of this error is
that you have tried a rewrite on a sequential file opened I-O, or on a relative file with access mode sequential also opened
I-O, without preceding it with a successful read NEXT.