This process is sometimes referred to as "Aryanization", and was only used for Czechs and Poles that had Germanic blood, since Slavic peoples were considered to be Untermenschen (sub-human).
This process is sometimes referred to as "Aryanization", though strictly speaking this is a misnomer, since Czechs and Poles were already members of the Aryan race. However, for the Nazis, Poles and East Slavs were considered to be Untermenschen (sub-human).