This term has been used to describe a peripheral agraphia syndrome characterized by problems spelling both words and nonwords, with case change errors such that upper and lower case letters are mixed when writing, with upper and lower case versions of the same letter sometimes superimposed on one another. Such errors increased in frequency with word length. These defects have been interpreted as a disturbance in selection of allographic forms in response to graphemic information outputted from the graphemic response buffer.
De Bastiani P, Barry C. A model of writing performance: evidence from a dysgraphic patient with an "allographic" writing disorder. Bollettinodella Società italiana di biologia sperimentale 1985; 61: 577-582