The dates of medieval documents are often not precisely known and so are catalogued with labels such as ‘early twelfth century’. While these labels are useful and meaningful for a medievalist, they present difficulties in a digital context in terms of searching, sorting, and aggregating existing descriptions. This paper will examine these challenges, propose an alternative way of modelling dates, and then make some suggestions for representing these in user interfaces. It draws on work for Models of Authority, a new project on Scottish charters of the twelfth century which is funded by the UK Arts and Humanities Research Council and which uses and extends the DigiPal framework (DigiPal 2010–14).