The "Links" tab is located in PlanSwift in the "Templates" tab.
The "Links" tab is a job-specific tab that is created every time you create a new job. It is used to create a database that you can link other items to, which allows you to be able to update information like pricing for that job or any other information for that job that you would like to be job specific information.
To link an item to that data base list, first right click on the item select properties. Next select "Advance Properties" and select the property you want to update. Then click on the insert property button which you can find on the top of the "Advanced Properties" window next to the Big Red X.
That will open up a window that allows you to find a path in PlanSwift to that database, which will be located under the job and the links. Then select the property in the database you want to use to update the item. This gives you the option to select a "Relative Link Path" or a "Full Link Path" to that property in the database.
After you hit "Ok", you will be able to tell if it linked properly because the result will show the information from the database.
There is a slight problem: when you create links to the "Links" tab from the "Templates" tab, the links will always have the job name rather than those "Relative Path" or the "Direct Path". This means that those items will always be linked to that specific job, so if you wanted to link another job, you would have to recreate the links in the new job. There is a way to get around this though: if you create the link in the "Estimating" tab, it will give you a very generic relative link to the database.
Then what you can do is copy that path into the items in your templates. Keep in mind, however, that the path only works once the item is created in the actual job, so when you are in the templates, that path won't do anything; it may show an error as well, but that error won't harm anything. As soon as you use that template and create it on the job then the path will work and it will pull in information from the links tab for the job that is open.
Another thing to remember about that relative path is that if you have the take off in folders in the "Estimating" tab, you need to add an additional "..\" to the path. For example: if I had the take off in a subfolder of a folder I would need my path to be [..\..\..\..\Links\Item\Property]