tags-case-fold-search

tags-case-fold-search is a variable defined in `etags.el'.
Its value is

default

Documentation:
Whether tags operations should be case-sensitive.
A value of t means case-insensitive, a value of nil means case-sensitive.
Any other value means use the setting of `case-fold-search'.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 21.1 of Emacs.