Skirts on transmit audio on the panadapter

When watching your transmit audio on the pan adapter you see the brick solid width as set in the transmit bandwidth (180-2900). But what are we seeing as the skirts broaden out. They slopes out about 3 kcs then flattens out at -125 DBM. So what are we seeing when this display is showing, is some of this in the audio chain in the radio like you might have in a soundcard.We know it is not being transmitted. Also several of us have been running a second slice(B) on the same frequency. sideband and mode as the slice (A) which is the transmit slice. we are seeing what we thought was our actual transmit audio as coming out of the transmitter. We see a little difference in the pattern. Is this the same as the slice A or is this a different pattern? And what is it.