devention DEVO-7 User Manual page 165

4）Usage method
The training switch should be work with the HOLD/TRN, showed is as belows,
During flying, if trainer pull TRN front and keep it,that means trainer already hand over
the controlled right to trainee. At the same time, the output date of open interface
should be the operated data of trainee. If trainer move away TRN, that means trainer
will get back the operated right from trainee and operate the model.
DEVO-7 Page 165 of 170