When creating a category we can assign it to a wet/dry split. First we need to create two categories (in Menu -> Menu Categories), one for wet, another for dry. They will then be mapped to your chosen department (Menu -> department mapping).
Now on the back office, we navigate to Menu -> Menu Categories
From here we can select the category we want to apply to wet/dry stock for reporting. To do this, first click the edit pen icon on the right.
Lastly we choose the category to report to, as illustrated above we have selected Wet and changed the reporting section to "1" which will enable the reporting for this category.