Here's an example of what you see: the normal picture is a clean schematic plot from the manuscript including obvious errors such as that below, which shows towns in Roman Africa as blue circles and a main road which I have colored green. Look carefully and you will see that the copyist has unaccountably shifted a section of the road upwards, closer to the sea (green area):
I want to show readers wordlessly how that defect can be repaired. In the picture below, you can see how the town and the section of road can be shifted downward and re-integrated into the route:
The coastal town that is moved here is Hadrumetum, now Sousse in Tunisia. The technique I have invented to highlight such changes is to show a gradual transition where the one disappears and the other gradually takes shape at the same time. Go to the website, http://piggin.net/plold.htm, and bring up the chart. If you hover your cursor over that pale yellow button at top right, the picture hereabouts begins to slowly change, as the following still picture, taken mid-way through the transition, shows:
You can see that a side road (to Cubin, an unidentified place) also shifts. So far I only have three of these transitions built into the chart. It took me a couple of days of tinkering with Javascript and cascading style sheets before I stumbled on a simple but effective technique involving the "hover" feature in CSS3, but it does take a while to write the code by hand for each case.
