These nouns have also usually been excluded from past treatments of reduplicated nominal patterns and subsumed under other rubrics, such as noun formations from biliteral
After marking the biliteral
sign, nb, 15 cm long, 3 cm at its widest point, upon the flattened surface with chalk, stone hammer-driven flint chisels were used to cut into the feldspar crystals.
Macdonald ("New Thoughts on a Biliteral
Origin for the Semitic Verb," Annual of the Leeds University Oriental Society 5 [1963-1965]: 63-85) and Christopher Ehret ("The Origins of the Third Consonants in Semitic Roots," Journal of Afroasiatic Languages 1 : 109-202).