The MPLAB ICE 4 using the MPLAB ICE 4 ICSP Adapter Board and the AVR JTAG (10 Pin) Adapter Board provides a legacy 10-pin 50-mil JTAG connection.
Direct Connection to a 10-pin 50-mil Header
Use the 10-pin 50-mil plugin connector on the “AVR JTAG (10 pin)” adapter board to connect directly to a target board with headers complying with the header pinout shown in AVR JTAG Pinout.