Bradley Lehman claims that the details of the intended tuning for the Well-Tempered Claivier are encoded in the squiggle at the top of the manuscript (related wikipedia link).
Are there other (claimed?) examples of common practice period manuscripts, or other documents that provide some indications on how to tune the instrument? (i.e. has someone found other similar cases?)
Alternately, have there been any papers that have research on how/where tuning indications were promulgated, but don't show anything similar to the squiggles approach? (i.e. has someone looked and failed to find similar cases?)
Basically, I'm somewhat skeptical of the claims made at the link above, but would be more convinced if there were other cases where tuning indications were included on score, so that the WTC wasn't a unique case.