AWR1843BOOST: Maximum transmit channels for beamforming

Hi, in the AWR1843 datasheet page 56 says:

"The three transmit channels can be operated up to a maximum of two at a time (simultaneously) for transmit beamforming purpose as required; whereas the four receive channels can all be operated simultaneously."

But in page 58  says:

"All three transmitters can be used simultaneously. For AWR1843, additional phase shifters are associated with Tx channels, and these can programmed on a per chirp basis"

So, how many Tx antennas can be used simultaneously, two or three?

thanks