Center text in orbeon PDF

I'm using orbeon 3.7 for my project. When I try to generate PDF using the "Template" method, everything work fine except that I can't find any ways to align the text at the center. Right now I'm using this code to plot my text:

<field left="200" top="269" size="100" value="co_name"/>

As you can see I can only set the left position to be 200 (or other value), what I need to know is there any way I can make something like :

center="true" or align="center"

Thanks in advance for your helps.

There is no such centering setting, sorry. You would have to modify the PDF processor to add support for this.

-Erik