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NNC-00418:

name "string" cannot be modified because it has children
Cause: A caller has attempted to delete or rename a global name, and that name cannot be modified because it has child names underneath it in the name space.
Action: Not normally visible to the user, except when using the name server control program. If the error occurs when using the control program, retry the failing operation with a name that is a leaf node. Otherwise, turn on tracing and re-execute the failing operation. If the error persists, contact Worldwide Customer Support.