Vapour Trails - Number Changing

Ive managed to get the vapour trails working and currently im just trying to fit the numbers to a few of my own planes (namely the POSKY A330-300)[sMOKESYSTEM]smoke.0=-900,-26.3,-77.4, fx_contrail_s.fxsmoke.1=-900,-26.3,77.4, fx_contrail_s.fx This is the coding that goes into the arcraft cfg file, but i need to know exactly what each number does. I think the second number is the position forward and behind a reference point on the plane. And the last number is the horizontal distance from the centre reference point...But what does the first number change???AND HOW do you change the verticle position of the trails to fit the wingtips????Help would be much appreciated, regardsMark.