The first pies, called "coffins" or "coffyns" were savory meat pies with the crusts or pastry being tall, straight-sided with sealed-on floors and lids. Open-crust pastry (not tops or lids) were known as "traps." These pies held assorted meats and sauce components and were baked more like a modern casserole with no pan (the crust itself was the pan, its pastry tough and inedible). The purpose of a pastry shell was mainly to serve as a storage container and serving vessel, and these are often too hard to actually eat. A small pie was known as a tartlet and a tart was a large, shallow open pie (this is still the definition in England). Since pastry was a staple ingredient in medieval menus, pastry making was taken for granted by the majority of early cookbooks, and recipes are not usually included. It wasn't until the 16th century that cookbooks with pastry ingredients began appearing. Historian believe this was because cookbooks started appearing for the general household and not just for professional cooks