CS3, Illustrator - Where Do X/Y Coordinates Measure from?

Question

I have a project where there are several PDF files. I'm using Illustrator to make these. It seems the point/line of origin is inconsistent from image to image (file to file). Where is the point of origin, by default, in CS3 Illustrator? It would be nice if, while I was positioning images, I could just say, "OK, x coordinate is 5.5 inches in this document, so it is 5.5 in that one." But it seems this is not the case. Anyone know how Illustrator sets these parameters?

Answer 1

According to the Adobe livedocs:

Rulers help you accurately place and measure objects in the illustration window. Rulers appear at the top and left sides of the illustration window. The point where 0 appears on each ruler is called the ruler origin. The default ruler origin is located at the lower-left corner of the artboard.

However,

To change the ruler origin, move the pointer to the upper-left corner of the illustration window where the rulers intersect, and drag the pointer to where you want the new ruler origin. As you drag, a cross hair in the window and in the rulers indicates the changing ruler origin.

But:

To restore the default ruler origin, double-click the upper-left corner of the illustration window where the rulers intersect.