Consider the example of a Business Rule that runs at order 100. Any variables defined in this Business Rule will be available to one that runs at order 200. In fact, the platform relies upon this behavior:
gs, and the likes are defined as global variables, and are available everywhere. You may like to think that ServiceNow just concatenates all the code in the Business Rules together, and makes one huge script that runs when a record is updated.
If you search the Web, you will find many ...