In Procore, a related item is link between two Procore objects. It is an option that's available in many Procore tools (i.e., Commitments, Documents, RFIs Submittals, and Transmittals). For example, if you are creating a submittal, you might want add a Procore drawing of the installation location or a photo of the item to be installed as a related item on the submittal. If you are adding a new punch item, you might want link a Potential Change Order (PCO) or a Commitment Change Order (CCO) as a related item, so the subcontractor can view the costs associated with the punch item.
When a user with 'Admin' level permission makes a Procore tool available on a project (see Set the Active Tabs on a Project), the objects created those Procore tools become available as 'Type' and 'Description' selections in the 'Related Items' tab of each supported tool (i.e., Commitments, Documents, RFIs, and Submittals).
See the links below to learn how to add related items using the Procore tools that support this feature: