There are two types of variable that relate hierarchies: hierarchy variables and hierarchy node variables.
Often, there are multiple hierarchies that could be used in a query. Hierarchy variables are used to provide a way for a user to choose a hierarchy when they execute a query. This is an more flexible alternative than fixing the hierarchy in the query.
Hierarchy node variables represent nodes within a hierarchy. As an alternative to fixing hierarchy nodes in the query, use hierarchy node variables to dynamically restrict a characteristic. With a hierarchy node variable, you can apply filters by hierarchy node in a query result.
There are two possible combinations of hierarchies and nodes:
Hierarchy Node Variable with a Fixed Hierarchy
Hierarchy Node Variable with a Hierarchy Variable