don't understand scale

[Douglass Davis]

I am using php mapscript, and i want to zoom in to a point.  I have two 
options:

zoomPoint and zoomScale...  I understand zoomPoint, because it just 
zooms by a percentage.  But, zoomScale, I am not understanding.  It 
zooms to a certain scale, which is a double.  What does that scale 
represent? What is the scale relative to?  The docs don't really explain 
this well.

The reason I wanted to do this, is because instead of  zooming in and 
out relative to the previous map's extent, it would be better if I had 
about 9 zoom levels, kind of like mapquest.  level 1 would show the 
states, level 9 would be a close up of the street.   But each of the 9 
levels would be a fixed zoom amount, relative to the size of the 
original extent in the mapfile possibly.   Is this difficult to do?

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