Astah User Guide
You can add hyperlink to diagrams and models. There are three ways to do so.
You can also add hyperlink by dagging a file directly onto diagram.
When you release the file on a diagram where no model is drawn, you have two choices.
If you choose the above option, a hyperlink will be added to the diagram.
If you choose the bottom option,
The hyperlink will be added with a text (File name).
You can choose what to add as hyperlinks. There are three types of Hyperlinks you can add.
You can search for hyperlinks that no longer exist.
This works only for "file" hyperlinks and does not work for URL, Diagram/model hyperlinks.