This is about a complicated application that holds 50 years of archived data. Some things are illogical and we can't change it because it's stuck in 50 years of rusted customs. But slowly I'll try and make it better.
There are tons of items ordered in a hierarchical structure. And sometimes the user will have a list of, for example, items which the user has found through a search action and has to do something with an item. At that moment the user will have no idea in which maps that item is ordered. So we wanted to give them some kind of map or breadcrumbs so they will know what the higher lying items are.
So the programmer says: "Why not give them links in those breadcrumbs so they can inspect the higher items?" But when the user decides he wants to inspect that higher item, the original search action will not be applicable anymore and be lost.
How do I design those links that they know the action is not reversible? He suggested an icon that indicates an external link (like wikipedia has ). Since there are no other external links in the application it won't conflict designwise. But I'm not sure it'll send the right message to the user.
Edit: One extra detail: There are external links. When a user wants to open a documentation/drawing about that item, the documentation needs to be opened in another program. They have an indication what kind of document it is, so they know what program will start. And they will get a warning pop-up screen about what's going on. They can cancel the action there. But the standing screen with the search results won't be affected.
Edit 2: At the moment the URL for the whole application is the same, which makes it hard to go back. I know the developers want to change that, but I/we don't know when that'll change.
Edit 3: I'm thinking of two solutions now. 1. Stop trying to make difficult links, the screen where the links are in is just an pre-information box. When an object really is selected the user can find out more about the objects parents in a more logical way. The conclusion is here that there is a reason not to add the links: It's less user friendly than it sounds. 2. Open the information directly in a overlaying screen. The user can open and close the screen without losing the search results. What the user wants is most likely to know more about the object they've found in the search.