how to get rectangles in pdfDocument

[Pedro]

Hi, I couldn't get any documentation for get the position of a table in 
a pdf document. I read the mailing list and it's appear that it's 
impossible. But I find PDRectangle class, if a table in a pdf document 
it's like some concatenated rectangles, if I get the position of these 
rectangles i'll be able to get the text inside of their by the position.
I'm searching documentation, or help, to get the position of a rectangle 
in a PDF document (or just get the rectangle), but I can't found any.
If someone knows how it do it, i´ll be very grateful.
Thanks