 While the content of environment variables remains unchanged upon storage, their names (without the "codice_66") are always converted to uppercase, with the exception of "pre-environment variables" defined via the codice_64 directive codice_22 under DR DOS 6.0 and higher (and only with codice_69 (for "allow lowercase names") under DR-DOS 7.02 and higher).In principle, MS-DOS 7.0 and higher also supports lowercase variable names (codice_70), but provides no means for the user to define them.Environment variable names containing lowercase letters are stored in the environment just like normal environment variables, but remain invisible to most DOS software, since they are written to expect uppercase variables only.