I'd like to keep my job
 

I'll have the best chance of that if I can answer this problem.
I've got a pdf that is used in all 67 PA counties. Rather than have 67 different forms with the address of the county office filled in each one, I need to have one form and have the County field filled when the form opens, either by XML metadata or some other source. Rather than get into further details, I'll stick with that question. Is it possible for a pdf to auto-fill a field on opening?

It looks like it's possible...
I did a search for "dynamic pdf" on google and I found a site:

http://www.fastio.com/forms/form1040.html

that does it for the 1040 form. That just shows you it can be done. I don't think they tell you how because from what I've skimmed, they want you to buy their product. (That's how I interpreted the last paragraph on the bottom of the page.) From other stuff I skimmed it appears that you can use PHP 4.2 to generate dynamic PDFs also.

PHP and dynamic PDF:
http://www.devarticles.com/art/1/503/2

Good luck, and hope you can keep your job!

I know someone who can do it. I will send him a PM and tell him to check out this thread.

Yes, it can be done. If you have access to the original PDF you can use an Adobe version of Java Script to do all kinds of cool things on the form.

How will you know which address to fill when the form opens?

Well, based on the location within the online collection, it'll get the address. I was thinking of having an XML document in the folder to read the address from. Can you cue the JScript to read from a source document like that?

That I don't know. It's been awhile since I looked at it but I don't think so. I don't know if you can do this or not but here is an idea. Assign each county a number. Have them enter the number on the form. When they exit the field where the number has been typed in the "on exit" event for that field is triggered. The function does a lookup and based on the number entered fills in the appropriate address. All this info is embeded into the PDF file.

Hmm. The goal for the client is for the form to auto-populate the address. Keep in mind that we're talking about maybe five thousand forms here, and it would suck to make the changes to each of the 67 copies every time, not to mention type the address in to thirty thousand plus forms. The counties are already numbered and are ordered in folders by that number. Can it cue off the folder using relative linking?

I don't know if it can read information outside of file or not. Check out this link

This can easily be done by taking advantage of the FDF layer of the PDF. You can manipulate the FDF by using JSP or ASP. You can also take advantage of the Java Script within the PDF Document.

The JSP or ASP model can perform lookups to a database or any other file to retrieve the information.

I noticed you find out the address from the web-site they call it from. You can then just use an FDF file. Fill out the address in a blank form and select File | Export | Form Data. This will create an FDF. Place this in the directory where the PDF is located and instead of calling the PDF, call the FDF. This will launch the PDF with the proper information.

If this isn't an option use the Java Script to create an FDF on the fly and load it into the browser with the correct information.

Let me know and I will try to locate a sample for you.