@entersafe 

My reasons were following:
* according to ISO7816-4 the general meaning of 0x6300 return code is 'warning', without any precising information;
* the OpenSC's iso7816.c generic driver defines the general meaning of return codes;
* according to ISO7816-4 this return code in the context of particular APDU can be seen as 'error';
* card driver can redefine the description of the particular return codes;

Finally, I have not strong conviction on this subject. 
If you vote for "<i>despite the ISO7816 definitions, in OpenSC any return code that is not 9000 is an error</i>" (that is the current state) I will follow.