Hi Sascha,
There are some differences in how the various RPC Servers react to this method. The various situations are best explained in the documentation
Documentation
But for your specific problem it should suffice to say that the library name is considered only if Natural Logon is forced, even if the Natural RPC Server is running without Natural Security.
If Natural Logon is not given, a Natural RPC Server (under Natural Security or Non-security) will not consider the library name.
If you are using a different RPC Server (C or Java for instance) the situation might be completely different though. In that case, please refer to the documentation link I already provided above.
Regards,
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