Most of the tablets are official military documents. However, the best-known document is perhaps Tablet 291, written around 100 AD from Claudia Severa, the wife of the commander of a nearby fort, to Sulpicia Lepidina, wife of the commandant of Vindolanda, inviting her to a birthday party. The invitation is one of the earliest known examples of writing in Latin by a woman. It has even been claimed that this is the earliest surviving letter known to be written by a woman in any language. 