I was wondering what evidence there is on the most effective means of presenting annotations to scholarly (or quasi-scholarly) work on the web.
I'm planning to put some articles onto the web, each of about 2000 words. Pop-science stuff, with a range of readership, from lay public to subject professionals.
On paper, we might use footnotes, endnotes or the like. The "...for dummies" books (pdf) use a wide left margin with "tip" and "technical stuff" icon plus text, as well as pull-outs and bordered boxes. Across the web, I see footnotes, occasionally sidebars, popup tooltips. WHATWG used a left-margin with callouts into the text
These annotations should be noticeable but not intrusive, insofar as that's possible.
The annotations I have in mind might be sentence or four, possibly containing links, but rarely (if ever) needing images as part of the annotation. (icons to indicate an annotation, and maybe the nature of the annotation, would be fine by me - as per the "... for Dummies" books)