Each end of a link has an associated start revision and an end revision that determines the range of revisions to which the link applies. The start revision is always fixed at the time of the creation of the link and is set to the first revision on the current branch. The end revision is under the user's control and may be fixed (or pinned), which puts an upper bound on the linked revisions, or floating, which does not. If a link end is pinned, it is always attached to the same version of the linked folder or file. If a link end floats, it moves from revision to revision, as new revisions of the linked folder or item are created.
By default, a link connects the tip revisions of the linked pair. The revisions selected for both links appear as columns on the Link pane.
Determining whether a link is visible on a given item is simple. If any of the revisions between the start and the end revision defined for the link are in the history of the selected item, it is visible. Otherwise, it is not.