Clusters can be passed into routines using either the cluster's name or the cluster's root name. In addition, clusters outside of the routine can be directly referenced from inside of the routine; they are globally available.

The routine is called by providing the routine name, the root cluster name, followed by the name of the cluster being passed into the routine. From inside of the routine, you can both read and write clusters. This provides an easy method to pass a lot of variables into a routine without having to pass in all the individual variable names.