“Accordingly ‘Entered at Stationers’ Hall’ on the title page of books was a form of warning to pirates that the owner of the copyright could and might sue. This requirement disappeared with the Copyright Act, 1911.” David M. Walker, The Oxford Companion to Law 1182 (1980).
stationers’ hall
Stationers’ Hall. Hist. The hall of the Stationers’ Company, established in London in 1553, at which every person claiming a copyright was required to register as a condition precedent to filing an infringement action.