Help CenterSub-folders act like tags or labels assigned to specs. Instead of changing the main folder structure, they let you create custom groupings inside a project—for example by phase, package, area, or any system that makes sense for your workflow.
You can assign or remove Sub-folders while creating or editing a spec. Simply enter the desired sub-folder in the Sub-folder field within the spec page.
Sub-folders can also be assigned in bulk, trough the Bulk Edit feature, just select the specs you need to assign Sub-folders to, and select the Sub-folder option from the Bulk Edit dropdown.
Type the Sub-folders you need to assing into the filed and hit the sumbit button.
It's also possible to assign colors to Sub-folders to make it easier to visually organize specs within a project. By clicking the edit icon next to Sub-Folders in the Filters panel, you can bring up a window in which you'll be able to assign colors, control whether those colored tags appear above specs, and remove sub-folders across the entire project if needed.
With Sub-folders already assigned, you can use the Filters panel to display only the specs associated with a the selected Sub-folders. 
You also have the option to adjust the Sub-folders filtering logic to be AND vs OR. If you go to the Project Settings tab, under the Filter Settings section, you’ll find the toggle button to edit this setting. This toggle is OFF by default. In the OFF setting, the “OR” logic is being used; when the toggle is ON, the “AND” logic is being used.
The "OR" logic, will display all the specs that have one or more of the selected Sub-folders assigned.
The "AND" logic, in turn, will only display specs that have all the selected Sub-folders assigned.