The number of phonograms is very restricted, but some signs have all these powers.
Thus signs, according to their employment, are said to be (I) wordsigns, (2) phonograms, or (3) determinatives.
Phonograms.Only a limited number of signs are found with this use, but they are of the greatest importance.
By searching throughout the whole mass of normal inscriptions, earlier than the periods of Greek and Roman rule when great liberties were taken with the writing, probably no more than one hundred different phonograms can be found.
As Egyptian roots seldom exceeded three letters, there was no need for triliteral phonograms to spell them.