>>From a math article I was able to find, "the slope computed as m = (y2 - y1) / (x2 - x1)." If you set the left-most part of the line at (0, 0) then a lower left to upper right line has a positive slope due to the fact that both the x and y values are increasing, where an upper right to lower left line has a negative slope (y goes from 0 to -something, while x increases). I'd say that a line with a positive slope goes "upward" and a line with a negative slope goes downward.
>
>Don't forget that 0,0 is at the top left & the x-axis increases down the screen. This makes a positive slope go from upper left to lower right. So in terms of "upwards slope" relating to to a mathematically positive slope then VfP is wrong & VB is right. In purely visual terms, I agree with you, that upwards is the otherway round. It's a poor choice of words for the documentation.

Len, are we having a cultural difference here?

In all my math classes, the X axis was horizontal and the Y axis was vertical. (0,0) was always somewhere on the lower left. Is the "usual" picture different in the UK?

Y Axis
|   /
|  / <<- Positive slope
| /
|/_______________ X Axis
(0,0)

For references of what's usual in the US see the following:
http://syllabus.syr.edu/cid/graph/Unit4b.html
http://math.rice.edu/~lanius/Algebra/stress.html
http://mathforum.org/library/drmath/view/52871.html
http://www.purplemath.com/modules/slope.htm
http://ourworld.compuserve.com/homepages/jtaylor114/DEFINITN/CalcGlos.html