chirograph

from The Century Dictionary.

• noun A contrivance for holding a beginner's hand in a prescribed position while be is learning to write.
• noun A deed which, requiring a counterpart, was engrossed twice on the same piece of parchment with a space between, in which was written a word or words, or the capital letters of the alphabet, through which the parchment was cut and one part given to each party, so that the correspondence of the two might be easily shown.

from the GNU version of the Collaborative International Dictionary of English.

• noun A writing which, requiring a counterpart, was engrossed twice on the same piece of parchment, with a space between, in which was written the word chirographum, through which the parchment was cut, and one part given to each party. It answered to what is now called a charter party.
• noun The last part of a fine of land, commonly called the foot of the fine.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun law, historical A kind of mediaeval document written in duplicate (or more) on a single piece of parchment, then cut across a single word, so that each holder of a portion can prove it matches the others.
• noun law, historical A papal decree whose circulation, unlike an encyclical, is limited to the Roman curia.
• noun obsolete The last part of a fine of land; the "foot of the fine".