Dr. Marta Ameri discusses the various types of seals and sealings, with emphasis on the fact that seals were primarily made to be reproduced. Many sealings, especially small molded objects, were not, it seems made for administrative purposes, but as objects in their own right, sometimes only showing an inscription of the seal. At times one seal is impressed on both sides of an object. There are also scenes of narrative sequences, or just plants that might have been talismans or commemorative objects; in the latter case we seem to have little evidence of the original seal or mold that would have been their primary support. Were they made for ceremonial purposes, after which the mold was discarded? A fascinating review which speaks to the wide variety of seal and sealing types and possible functions.
The discussion brings up a point not appreciated enough when people examine seals in great depth; most of these engraved objects were made as masters to be impressed upon something else. In many cases that we know of, that material was terra cotta. But was there something else? The amount of copies in Indus excavations is so far very limited compared to Mesopotamia, but is it because a library or repository has not yet been discovered?