ardupilot/libraries/APO/AP_Var_keys.h

#ifndef AP_Var_keys_H
#define AP_Var_keys_H

enum keys {

	// general
	k_config = 0,
	k_cntrl,
	k_guide,
	k_sensorCalib,

	k_radioChannelsStart=10,

	k_controllersStart=30,

	k_customStart=100,

	// 200-256 reserved for commands
	k_commands = 200
};

// max 256 keys

#endif