The number 281 could be the page number of the assembled edicts or it could be the number of the 281st Ukaz of the Reign of Ekaterina II.
There is another Russian document currently for sale ebay that has a bit more historical value, a letter signed by Prince Kropotkin, Commander of the Pärnu Grenediers, King Fredrich Wilhelm IV of Prussia Regiment, on the regimental letterhead in the year 1862. The city of Pärnu is the third largest city in Estonia.
David