Definition of "undifferenced"

In speculating upon this curious controversy, the question naturally arises, whether a plain and undifferenced coat-armorial descends to a man's heirs, according to the ordinary rules of heritable succession, or whether it happens […]

1863, George Seton, The Law and Practice of Heraldry in Scotland, page 336

Nowadays, even the successive heirs to the principal or undifferenced coat of arms usually rematriculate after a few generations, or bring up to date a pedigree in the Public Register of Genealogies, both for the purpose of putting on […]

1956, Sir Thomas Innes of Learney, Scots Heraldry: A Practical Handbook on the Historical Principles and Modern Application of the Art and Science, Genealogical Publishing Com, page 109