Lines were ruled on the surface of the page with a knife or stylus The Book of Deer has 22 – 26 lines per page. Each gathering has six double pages. Once prepared the scribe was ready to start writing. A quill pen made from a large feather and black ink made from oak gall, also known as an oak apple, was required. The Gospels in The Book of Deer were written by a single scribe who would have copied from another manuscript. It is written in the style of print known as Irish minuscule with the letters hanging below the line. The language is an ancient version of Latin.
Work of the Scribe
III.1. Structure of a Book, MMM (ceu.hu)
It is likely that the scribe copied the contents from a relatively ancient book. This is suspected since the Latin used is an older version of the language than was in vogue at the time. It also is described as having many mistakes which would indicate that the scribe was not familiar with the language of the text he was copying.