[Therion] xtherion trace line, convert to curve

Are there any instructions regarding Xtherion's 'trace line' and 'convert to curve' line editing features? I expect there are - just cannot find them. The 'convert to curve' seems to take a line with straight segments and converts it to a smooth curve, so perhaps not so complicated. I have not been able to get any useful insights after playing with 'trace line', except that it adds two buttons to the interface. Thanks Bruce