From In-Portal User Manual

• Relation ID – this is a read-only field, the internal system ID of the relation, guaranteed to be unique throughout the system. It is blank when a new relation is created.
• Item – this is a read-only field, displaying the name of the item that you are creating a relation to, and its type. In the current version, links can be related to categories, articles (if In-newz is installed) and topics (if In-bulletin is installed).
• Type – this field designated the type of the relation. A ‘reciprocal’ type denotes a two-way relation, and ‘one way’ – a one directional relation, from the link to the item. 
• Enabled – this field is the status flag of the relation.
• Priority – this field is the numerical priority of the relation.