Where is the Origin (x,y) of a PDF page?

Question

I am using iText to create my PDF files.

I want to position text at some specific place in the document using the method I found here:

Answer 1

Please note that in most PDF generators, PDF page origin is from the left bottom (0,0).

1 inch = 72 points and 1 cm = 1/2.54 inch = 0.3937 inch = 28.3 points.
where,
(lower left x coordinate)l l x=margin from left.
(lower left y coordinate)l l y=margin from bottom(bottom of rectangle)
(upper right x coordinate)u r x=width of article
(upper right y coordinate)u r y=margin from bottom of upper boundary of article.

To draw a Rectangle in PDF, using such generators, which contain A-4 size pages then, you need to define Rectangle as:

rectangle = new Rectangle(25, 25, 575, 820);
rectangle. set Border(Rectangle.BOX);
rectangle. set Border Width(1);
document.add(rectangle);