You could use substring formulas for this, I suppose - see the attached sample form. Right click the link in the post header, and select the option to save the file locally. Right click the saved file, and then select Design to open. Note - you may want to add some error handling to this, or not run the rule if the string isn't 10 chars long, or something like that, this is just a rudimentary sample.
Hilary Stoupa
