[Elecraft] P3 Basics

[Pete Meier]

Ok folks,

I'll try this question again. On the P3 display there is a purple line that move out or in when you set the SPAN width. This is NOT the VFO A or B marker!
I would like to understand what it signifies and if there is any control over it's position other than the SPAN setting and why. 
I find on some bands it up the scale, like on 20 meters CW, with Span set at 40 it's way up at 14.186.00 when I am at 14.010.00
But when I switch to 30 meters CW Span at 40 also its at 10.115.45 while on 40M CW at 40 Span it's at 7.008.00
So it confounds me what it signifies as it varies so much between bands at the same settings.

Please politely enlighten me.

Thanks,

Pete WK8S