&4 Only '0-9', 'A-Z', and '_' are permitted in the identification

What causes this issue?

You can use only the characters "0-9", "A-Z", and "_" (underscore) in
the identification.

System Response

The identification you entered contains invalid characters. The data
cannot be saved.

How to fix this error?

Change the identification so that it contains only the valid characters
listed above.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.