In the Pro or Server edition, you can create a custom attribute with a data type of Item Link and select a linked file. This link would show up in the Document > Links inspector under Incoming Links.
Currently you have to sfroll and find the item in the dropdown in the Custom Info inspector.
It would be nice if you could drag and drop a file onto such a dropdown, but @cgrunenberg would have to comment on the feasibility of that.
This is not going to make a custom attribute applied to the original file, i.e., you’d have to st the attribute on each file, pointing to the other.
You cannot assign more than one item link attribute at a time.
You also can’t just add these attributes on an ad-hoc basis without going to the Data preferences.
There is an app called Hook that maintains a database of documents linked to each other. It works with DevonThink and many other apps as well. This might be a better solution to connect documents from disparate apps. Hook App Homepage
I would also suggest looking at the Hook app. Would be amazing if DT team hard baked that into DT, it’s so useful, but hook does it nicely on the mac (not iOS).
I’m looking for a similar function. Although in my case I would actually prefer the cross reference to reside within an annotation in the PDF file itself. I’ve found a workable solution, but it behaves a bit inconsistently.
It seems like the PDF highlights/annotations viewer in DEVONthink cannot handle hyperlinks. However, some annotation types created in the application Skim can contain hyperlinks. Anchored note in Skim can have rich text content. So I paste the DEVONthink hyperlink into the anchor note. Exporting the annotation from Skim maintains the hyperlink. However, when viewing the PDF within DEVONthink, the link in the anchor note becomes inert. The note is also missing its hyperlink when creating a summary of the PDF’s annotations using DEVONthink’s “Summarize highlights” script.
As a bit of an aside, is anyone interested in trying their hand at creating a Skim notes template for exporting annotations as markdown including deep links to the cited page in DT? I found a markdown export template on the Skim wiki, but I’m new to this and it’ll surely take while before I get around to learning how to make this template myself.
Would you mind sharing some examples of how you use Hook and DT together?
I use Applescript to generate markdown links for DT notes and copy that in my notes within and outside of DT. I want to see if Hook has a more efficient workflow.