You can use the Nr parameter to perform a record query search so that only results tagged with a specified dimension value are returned. For example, say you have a dimension tree that looks like this, where Sku is the dimension root and 123, 456, and 789 are leaf dimension values:

Sku
  123
  456
  789
  ...

To perform a record query search so that results tagged with any of these dimension values is returned, use the following:

Nr=OR(sku:123,OR(sku:456),OR(sku:789))

To perform a record query search so that only results tagged with the dimension value 123 are returned, use the following:

Nr=sku:123