In my earlier work on this book, I translated "Mahnungen" as
"Recalls". I assumed that the reference was to the recall notices that
many libraries (including the one I used to work for) send out when an
item is due for return or renewal.
However in the chapter on Queries, it is mentioned that these
"Mahnungen" are associated with a fine of 2 euros per item! This
must mean that they are not recall notices but overdue notices issued
*after* the loan has expired. The name for the associated table should
therefore be "Overdues", not "Recalls".
Sorry to put a spanner in the works at this late stage!