https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1... > Uppercase and lowerc

https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1... > Uppercase and lowercase letters shall retain their unique identities and shall not be folded together. > The name space of environment variable names containing lowercase letters is reserved for applications.