I normally just use the parameters screen to add additional tags, but IIRC I did have to one time tweak (VERY carefully) the file:
Code:
C:\Users\......\AppData\Roaming\calibre\plugins\diaps_editing_toolba
g_SpanDivEdit_settings.json
Don't recall exactly why, but I THINK it was because I wanted to modify a tag that wasn't in the original distribution
Been awhile since, once I had everything set, there hasn't been any reason to change