Doubt about Response APDU in case2 and case4

[shyjarod]

Recently, I have read ISO/IEC 7816-3 spec to learn APDU command. But I have a doubt about Response TPDU in case 2 & case4.
As we all know, there are the four structures of command APDUs.
In case2, if process aborted, it returns 6CXX.

In case4, it returns 61XX.

What is the difference between "6CXX" and "61XX"?

[UNKNwYSHSA]

6CXX means to process the current APDU command, the CAD need re-issuing same APDU command on the same origin logical channel number as that of the current APDU command with the corrected length.

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<< 80 01 00 00 00 // The APDU command; From ISO7816-3, the APDU command is in CASE2;
>> 6C 07 // Corrected length is 0x07;
<< 80 01 00 00 07 // Reissue the APDU command with corrected length;
>> 11 22 33 44 55 66 77 90 00 // APDU command responsed data.

61XX means the CAD need send GET RESPONSE command with Le as the value of XX to got the response data of the current APDU.

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<< 80 01 00 00 05 11 22 33 44 55 00 // The APDU command; From ISO7816-3, the APDU command is in CASE4;
>> 61 07 // Corrected length is 0x07;
<< 00 C0 00 00 07 // Reissue the APDU command with corrected length;
>> 11 22 33 44 55 66 77 90 00 // Got responsed data.

[UNKNwYSHSA]

If you want to understand more, class javacard.frameword.APDU in specification Java Card API document describes more details. Key word is ISO7816.SW_BYTES_REMAINING and APDUException.NO_T0_REISSUE.