completion-ignore-case

completion-ignore-case is a variable defined in `C source code'.
Its value is

nil

Documentation:
Non-nil means don't consider case significant in completion.
For file-name completion, `read-file-name-completion-ignore-case'
controls the behavior, rather than this variable.
For buffer name completion, `read-buffer-completion-ignore-case'
controls the behavior, rather than this variable.