German mixed inflection takes its name from
the fact that it has endings from both the strong inflection and
the weak inflection. The mixed inflection is used after the indefinite
article "ein" and after "irgendein" e.g. "(irgend) ein kleines Kind",
after "kein" or after possessive pronouns e.g. "ihr kleines Kind".
(http://www.canoo.net/services/OnlineGrammar/Wort/Adjektiv/Deklinationstyp/Gemischt.html?MenuId=Word3132 20.11.06)
Mixed inflection is a characteristic of lexemes, not individual tokens.