The links are to the documents in the DEVONthink database-from there you could send them to an app that supports the particular filetype using the iOS 'Open In' command.
For example, you could link a PDF in the DEVONthink Mac database to a task in OmniFocus Mac. When you click on the link in OmniFocus Mac, the document would open in DEVONthink Mac and from there you can open the document in Preview, Skim, etc.
If you also sync that document from DEVONthink Mac to DEVONthink To Go (universal app for iPad/iPhone, then click on the link in OmniFocus iPad/iPhone, then the document opens in DEVONthink To Go. At this point, you would click on the 'Open In' command, select a supported app such as GoodReader, where you could make annotations, etc., and send the edited document back to DEVONthink To Go.
For example, you could link a PDF in the DEVONthink Mac database to a task in OmniFocus Mac. When you click on the link in OmniFocus Mac, the document would open in DEVONthink Mac and from there you can open the document in Preview, Skim, etc.
If you also sync that document from DEVONthink Mac to DEVONthink To Go (universal app for iPad/iPhone, then click on the link in OmniFocus iPad/iPhone, then the document opens in DEVONthink To Go. At this point, you would click on the 'Open In' command, select a supported app such as GoodReader, where you could make annotations, etc., and send the edited document back to DEVONthink To Go.