Abstract: Improvements in a fenceless electronic animal control system comprising portable stimulation units attached to the animal and rf transmitters defining an area, with the stimulation of the animal based on the transmission received by the portable unit. The transmitters transmit signals containing multiple codes to permit selective stimulation of pre-defined categories of animals and to insure a continuous electronic signal boundary. Portable units include the capability of transmitting signals in response to in inquiry signal from a separate transmitter thereby providing confirmation of the location and identify of the animal.