add-log-current-defun-header-regexp

add-log-current-defun-header-regexp is a variable defined in `add-log.el'.
Its value is

"^\\([[:upper:]][[:upper:]_ ]*[[:upper:]_]\\|[-_[:alpha:]]+\\)[ 	]*[:=]"

Documentation:
Heuristic regexp used by `add-log-current-defun' for unknown major modes.
The regexp's first submatch is placed in the ChangeLog entry, in
parentheses.

You can customize this variable.