The official filing date of the patent application for 'Writing Board' by Rebecca A. Schroeder. The application detailed the invention's design and functionality.

The United States Patent and Trademark Office (USPTO) officially granted US Patent 3812623A to Rebecca A. Schroeder. This patent protected her invention from being copied without her permission.

Based on standard patent terms at the time (17 years from the grant date), the patent would have expired around May 20, 1991. After this date, the invention entered the public domain, meaning anyone could freely produce and sell Glo-Sheets without requiring permission from Becky.