Example 1: 

Subtract the continuum of channels 10~100 and 300~350 in spw 0 (assuming that the line is in channels 101~299). Note that we also exclude edge channels, e.g. the first 9 channels. We use a fitorder of 0 (default). 



Example 2: 

subtract continuum across all spw, assuming that the line sits at 23.694GHz with a 20 MHz width. We use fitorder 1 for the large frequency range.  

uvcontsub(vis='myMS.ms', fitspw='23.684~23.704GHz', excludechans=True, combine='spw', fitorder=1)