Understanding the status code for RUI3's callback

I am wondering the meaning behind the status code for the function assigned to registerJoinCallback, registerJoinCallback and registerSendCallback.

After searching the forum and documentation, I can only found the following

for registerSendCallback,

void sendCallback(int32_t status) {
//0=EVT:SEND_CONFIRMED_OK (For confirmed uplink receive ACK and unconfirmed uplink)
//4=EVT:SEND_CONFIRMED_FAILED (For unconfirmed uplink did not receive ACK)

Can someone help me pinpoint the location in the RUI3’s documentation?