I have been taking a look at the FRDM-K64F schematic and I have a question.
Can this board be used to program/debug external targets through the openSDA JTAG pin header (J10, page 3)?
Yes: Using FRDM-K64F Board to debug another Kinetis Board
I hope this helps,
In that article the connector used to debug an external target is J9.
So I guess that J10 is used to program/debug the FRDM-K64F on board cpu using a JTAG programmer like Segger J-LINK or similar.
Am I right?
yes, that's correct. J10 is used to flash/debug the OpenSDA K20 device on the board.