We added an example of the internal linking in a checklist in the Featured (Snippets) section on the home page. You can add the Branching Emergency Snippet to your My Checklists and then check out the source in the editor. That is a very advanced example of linking.
For a simple link inside a checklist you would add an ID value to the List, Section or Item and then use this syntax within Label 1 or Label 2…
[Jump to Postflight](gotoAndReturn:#postflight)
That will also popup the history dialog. If you don’t want that, then…
[Jump to Postflight](goto:#postflight)
For externally linking to another checklist you would add an ID for the Checklist (root node in hierarchy). This ID should be universally unique, so having tail number in there good. Then to make the link you use this syntax within Label 1 or Label 2…
[Preflight Complete](gotoAndReturn:n6472g-preflight)
If you just want to jump without the history popping up then…
[Preflight Complete](goto:n6472g-preflight)
If you want to deep link which means jump to external checklist and jump to internal ID in checklist, then you would add an ID for the internal List, Section or Item and then…
[Preflight Complete](gotoAndReturn:n6472g-preflight;#internal-id-goes-here)
Linking Command Reference
There are many commands that can be used for linking. Here is the Linking Command Reference.