According to this theory, the alphabet was transmitted in oral form or on wood only, until it was finally put into a written form on stone inscriptions in early Christian Ireland.
Later scholars are largely united in rejecting this theory, however, Macalister's theory of hand or finger signals as a source for ogham is a reflection of the fact that the signary consists of four groups of five letters, with a sequence of strokes from one to five.
The etymology of the word ogam or ogham remains unclear.
One possible origin is from the Irish og-úaim 'point-seam', referring to the seam made by the point of a sharp weapon.
Alternatively, the Ogam Tract credits Ogma mac Elathan (Ogmios) with the script's invention.The fact that the order of the letters is in fact BLFSN led the scholar Macalister to propose that the letter order was originally BLNFS.