I got it from another Topic when I searched for Consumption Warehouse.
… later in the Topic Emre mentions the PCW filter. According to that ^ you could use instead something like one of these constraints:
C.Warehouse=="$1" // get var from list
C.Warehouse=="Local Warehouse" // specific warehouse
... or ...
(PCW=$1) // get var from list
(PCW=Local Warehouse) // specific warehouse
The $1 is supplied by the previous list, in this case, a list of Warehouses. For each Warehouse, the second Report Tag runs. The $1 changes for each iteration of the list.
Correct. When we want to specify output delimiter (comma) we must specify the columns from the field-list, starting at 0. So it lists Warehouse names Alphabetically, with a comma separator. Each item in the list is fed to the next Report Tag in the $1 variable, and that next Report runs multiple times - once for each item in the list.