Copy a structured keyword list from one project to another existing project?

I have a project with a highly structured keyword list (i.e. with keywords organised into a number of levels). I’d like to be able to take those same keywords and their organisation structure to another project. Is this at all possible?

I know if I copy a document from one project to another the keywords go with it, though without any structure. And I could create a blank project by duplicating an existing project (with keywords) then deleting all the documents. But in this instance I want to copy the organised keyword list from one project to another existing project.

I guess the more general question is, how are keywords stored in a project and do users have any access to them other than through the keyword window?

You can do this by opening both projects and their Project Keywords panel (from the Project menu), then selecting all the keywords in the panel from Project A and dragging and dropping into the keywords panel of Project B. Drag and drop will maintain the hierarchy as well as the original colours.