While I am not an expert on the usages of "Sede Vacante", I can tell you that "the seat is vacant" refers to any period of time when a bishopric (or higher, like the Vatican) is between bishops. The previous bishop has died; a new one has not yet been chosen. I collect coins of the bishopric of Eichstätt (in central Bavaria, in the Altmühl valley; existed as a political entity 742 to 1806; still a bishopric today). Eichstätt minted at least three "Sede Vacante" coins -- a 1757 Taler, a 1781 Taler, and a 1790 Doppeltaler. I have not researched how many other German bishoprics, if any, minted "Sede Vacante" coins.

As a child, I lived in Eichstätt from December 1948 to May 1952. That view of the "Willibaldsburg" (the castle shown on the coin) is roughly the one I had out of the window of my room. Note the names on the leaves of that coin. I tripped across the online fascimile copy of an 1845 catalog of Eichstätt coins that lists those names as part of a lengthy description of the images on this coin.

I was pleasantly surprised to find information on other German bishoprics that minted "sede vacante" coins in the 16th, 17th and 18th centuries. In going through the photos found on Google, there is one that shows a postcard with a cathedral and some coin images. It notes a Zepernick classification system (never heard of it before).

This change from the ANS Colonial Newsletter might get confusing in that the Journal of East Asian Numismatics also uses JEAN and just published their 10th issue.

I’ve had about a half dozen solutions/answers from E-Sylum readers. Very impressive!