Global List definitions are not exported with a process definition. You have to consider a Global List like a database table when you manage multiple environments (e.g. development, staging, production)
This means that when you export a process definition from development to production, you have to check if the Global Lists used by the web form are already in production too.
To deploy a Global List from development to production, WorkflowGen administrators just have to export the Global List as an XML file and import it in the production server.
Then, if needed, you can change the Global List settings (such as the databinding settings) and content for production usage .
To manage multiple versions of a global list, you have to duplicate the global list and rename the new list (e.g. rename MYVLIST_V1 to MYLIST_V2).