Is there a way to create a global property, for example, if you had a page type with a heading which was the same on every page, is there a way to make the property linked so you can change it in one place and it woul dchange it on every instace of that page type?

 I know I can just leave it in the template and change it when necessary etc... but I want to be able to change the value through edit mode. without having to goto every page and copy & paste the value as there may be thousands of that page type.