A namespace called the blackboard is used for communicating values across all namespaces.
The blackboard namespace is not attached to any document or VLX application. You can set and reference variables in the blackboard from any document or VLX application. Use the vl-bb-set function to set a variable, and use vl-bb-ref to retrieve a variable's value.
For example, the following sets the foobar variable to a string in the blackboard namespace:
(vl-bb-set 'foobar "Root toot toot") "Root toot toot"
The vl-bb-ref function returns the specified string. The following uses the vl-bb-ref function to retrieve the value of the foobar variable from the blackboard namespace:
(vl-bb-ref 'foobar) "Root toot toot"
Setting or retrieving variable values in the blackboard namespace has no effect on variables of the same name in any other namespace.