In Lebor Ogaim

In Lebor Ogaim ("The Book of Ogams"), also known as the Ogam Tract, is an Old Irish treatise on the ogham alphabet. It is preserved in R.I.A. MS 23 P 12 308–314 (AD 1390), T.C.D. H.3.18, 26.1–35.28 (AD 1511) and National Library of Ireland MS G53 1–22 (17th century), and fragments in British Library Add. 4783. It does not bear a title in the manuscripts, but it is mentioned in the Auraicept na n-Éces (2813f.) as amal isber in leapar ogaim, whence the commonly used title. The Ogham Tract is independent of the Auraicept, and is our main source for the Bríatharogaim.

The Ogam Tract also gives a variety of some 100 "scales" of variant or secret modes of writing ogham (92 in the Book of Ballymote), for example the "shield ogham" (ogam airenach, nr. 73). Even the Younger Futhark are introduced as "Viking ogham" (nrs. 91, 92). Some of these are word lists based on the alphabet, and some seem to involve a numerical system of tallying. Most however, are simply variations on ways of writing the alphabet. They are examined for their significance by Macalister (1937) and by McManus (§7.11, 1991).