the first manuscript, which covers folios 1-12v (six bifolia), was compiled and written in the late 11th century or possibly at the beginning of the 12th. the fine minuscule script suggests the work of two professional scribes, and glosses were added by later hands. one of these glossators has been identified as the scribe "h" who was also responsible for adding glosses to the lebor na huidre. like the latter work, this part of rawlinson b 502 may therefore have been a product of the monastic scriptorium of clonmacnoise, co. offaly.