If I can add something i remeber tye explaining me that on windows %ENV keys are case retentive: this was made because on such OS ENV is implemented in this way so %ENV reflect the behaviour.

Consider the following two examples:

set foo=bar & set FOO=BAR & set FOO
foo=BAR

set FOO=BAR & set FOO=bar & set FOO
foo=bar
[download]

So for sure also %ENV keys (not just values) must be treated as special, very funny and tricky, strings. In short: do not do it! keep %ENV keys uppercase ASCII plain strings and values as close as possile to a plain ASCII string

L*