When setting up your Cradle schema, one of the most important elements that must be considered is your cross reference parameters (traceability settings). Within the cross reference parameters, you have the ability to define your link type. A link type is a verb or phrase used to describe the relationship between two pieces of data. Link types should be defined very early in the project, so you can establish required link rules to control the types of data that can link in the project. Even though veteran Cradle users are quite familiar with link types, I have found that many aren't familiar with link groups
A link group is a named set of link types. If you ask Cradle to search based on a link group or use a link group when defining a navigation, Cradle searches using ALL of the link types specified in the link group. You will want to include link types that are related to each other in one link group. Name this link group as something that is a description of the relationship between the link types. For example, if I have four link types that can be used when linking one requirement to another requirement, I would create a new link group called Requirement Traceability, and I would add those four designated link types to the link group. When I query the data based on links, I can specify the link group (you will see link groups on the link types drop-down list in Query Details), and you will receive all of the linked requirements that are linked with either link type assigned to the link group.
To create a new link group, go to the Cross Reference Parameters section of Project Setup. Select the Link Groups tab. Select New and name the link group. With the new link group highlighted, select Edit. Now, click on the link types that you wish to add to your link group, and save your project settings.