Author’s Alterations have been charged in the printing trade for many years.

Author's alterations are changes made to a job after it has already been sent to a printer for production. The change could be in copy, specifications or both. If you (the customer) make changes to your original file, these are AAs and the printer can charge you for making them. If, however, the errors are attributable to the printer, these are PEs (printer's errors) and you don't pay for correcting them.