Probatio pennae is the medieval term for breaking in a new pen, and used to refer to text written to test a newly cut pen.

A scribe

Scribe

A scribe is a person who writes books or documents by hand as a profession and helps the city keep track of its records. The profession, previously found in all literate cultures in some form, lost most of its importance and status with the advent of printing...

 would normally test a newly cut pen to see if it wrote well by writing a few lines of text on a piece of blotting paper

Blotting paper

Blotting paper is a highly absorbent type of paper or other material. It is used to absorb an excess of liquid substances from the surface of writing paper or objects. It is also commonly used as a beauty tool to absorb excess oil from the skin.-Manufacture:Blotting paper is made from different...

. Sometimes these blotting papers survived due to being used afterwards as book binding material; they often provide unique, less "serious" textual material that would otherwise have been lost. A famous example is "Hebban olla vogala

Hebban olla vogala

Hebban olla vogala, sometimes spelt hebban olla uogala, are the first three words of a 12th century fragment of Old Dutch.The fragment was discovered in 1932 in the margin of a Latin manuscript that was made in the abbey of Rochester, Kent and that is kept in Oxford...

", the first fragment of Dutch literature

Dutch literature

Dutch literature comprises all writings of literary merit written through the ages in the Dutch language, a language which currently has around 23 million native speakers...

, which survived from a tenth-century probatio pennae.